01_2008_Tech_Jargon

Fast Trackto

Tech Jargon

By Team Digit

CreditsThe People Behind This Book

EDITORIALRobert Sovereign-Smith Assistant EditorRam Mohan Rao Copy EditorNimish Chandiramani Copy EditorBhaskar Sarma WriterR Srikanth WriterAbey John Writer

DESIGN AND LAYOUTShivshankar Pillai, Vijay Padaya, Sivalal S Layout DesignersSivalal S Cover DesignHarsho Mohan Chattoraj Illustrator

© Jasubhai Digital MediaPublished by Jasubhai Digital Media, a part of 9.9 Media. No part of this book may be reproduced,stored in a retrieval system or transmitted in any form or by any means without the prior writtenpermission of the publisher.

January 2008Free with Digit. Not to be sold separately. If you have paid separately for this book, pleasee-mail the editor at [email protected] along with details of location of purchase, forappropriate action.

Behind The Word-Screen

You’ve doubtless noticed that of late, tech phrases, terms, andnames float about freely, intermingled with regular speech.We know you know half those terms (or a little more, or a

little less), and those that you do, there’s a good chance you’re notsure, or you “know” wrong, or you know half of what’s to beknown. If you deal with technology in any way—and you do, sinceyou’re reading Digit—you’d be happy knowing all those words thatfloat around. That’s our (simple) purpose here: to demystifyeveryday tech terms.

We’ll extend that a bit and say that we’re not just demystifyingthings; we’re also explaining things where it is warranted. Thefollowing can be read cover to cover if you’d like, if you need a basiceducation of sorts, or it can be used as a reference for when youcome across a new term—even, for example, in Digit.

We’ve covered pretty much everything you’d need to know inan everyday sense—the basic hardware of a computer, storage,peripherals (things like printers), the devices that delivermultimedia, portable gadgets, software, and network terminology.

We’d encourage you to flip through these pages even if youthink you’re familiar with most terms—for the reason that some ofthe terms we’ve covered go into somewhat in-depth explanations,which can be useful, and also because a term might not actuallyrefer to what you think it does!

In the end, it’s about being aware. So allow us to rip off thetagline of a popular technology site, modify it just a little bit, andstate that as the raison d’être for this book: It feels good to know.

Introduction

CONTENTS

Chapter 1 Core Hardware 91.1 The Motherboard 101.2 RAM 181.3 Processors 221.4 Code-names 27

Chapter 2 Storage 292.1 The Hard Disk 302.2 Optical Drives 402.3 Flash Drives 49

Chapter 3 Peripherals And Other Components 513.1 The Power Supply Unit 523.2 Printers 563.3 Laser Printers 603.4 Inkjet Printers 613.5 Scanners 633.6 Mice 663.7 Keyboards 683.8 Webcams 703.10 Gaming Accessories 723.11 UPS 74

Chapter 4 Sight and Sound 774.1 Monitors And TVs 784.2 Graphics Cards 864.3 Speakers and Headphones 954.4 Sound Cards 1014.5 Interfaces 104

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Chapter 5 Portable Gadgets 1075.1 Laptops 1085.2 Mobile Services And Standards 1135.3 Mobile Phones 1165.4 Cameras 1195.5 Connectivity 1235.6 Portable Media Players 126

Chapter 6 Software 1296.1 Operating Systems 1306.2 General Software Terms 1336.3 Programming 136

Chapter 7 The Network 1477.1 Technologies 1487.2 General Internet Terms 1517.3 Web 2.0

Chapter 8 Everything Else 1478.1 Computer Science Fundamentals 1638.2 Upcoming Technologies 1648.3 Enterprise IT 1658.4 Internet Culture 176

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If we're going to talk about terms, definitions, and jargon, thebest place to begin would probably be where it all starts -namely, at the CPU and motherboard. Let's also not forget the

RAM!

Core Hardware

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1.1 The Motherboard

1.1.1 Audio socketsA set of sockets that allowed speakers and a microphone to be con-nected, usually three in number. With multi-channel audiobecoming common, the number of sockets has risen to six. Thefunction of each of these sockets is configurable from the audiodriver.

1.1.2 AGPThe Accelerated GraphicsPort is present only in veryfew new motherboards; it isbeing phased out. This was aslot dedicated to enhancethe graphics capabilities ofthe system by allowing ahigh-speed direct bus to theRAM, unlike PCI, the otherprevalent bus. (A bus refersto a channel that is used totransfer data.) It operated at66 MHz and had a 32-bitwidth. The AGP specifica-tions have passed throughthree revisions (AGP 1, 2, and3). The original AGP specification, now referred to as AGP 1, speci-fied only 1X and 2X speeds. It also mandated an AGP slot that pro-vided 3.3 V. AGP2 extended support to the 4X mode of operation. Italso specified an AGP slot that provided 1.5 V, but AGP2 cardscould work in the older AGP1 slots. To maintain backward com-patibility to AGP1 cards, a Universal AGP Slot allowed cards of bothversions to be run in it. AGP3 supported speeds up to 8X and wouldonly work in slots that operated at 1.5 V.

The AGP slots differed in the construction, so that 3.3 V and 1.5V slots and cards were not compatible: the 3.3 V AGP slot has a par-

Screenshot 1: 1.5 V AGP slot.jpeg

Screenshot 2: 3.3 V AGP slot.jpeg

tition towards the left, whilethe 1.5 V slot has a partitiontowards the right. Each ofthese slots also had a Pro ver-sion that extended the slot abit to the right. The AGP Proslot was for those cards thatneeded additional power(which was supplied by thePro extension). The cardswere also similarly-notched.Maximum data transferspeeds offered were: AGP 1X:266 Megabytes per second;AGP 2X: 533 Megabytes persecond; AGP 4X: 1066Megabytes per second; AGP 8X: 2133 Megabytes/second.

1.1.3 BIOS / CMOSThough often interchange-ably used, the two termsrefer to different things.BIOS (Basic Input OutputSystem) refers to a set ofinstructions that are criticalfor the functioning of thesystem. These instructionsinclude information aboutthe components connectedto the motherboard, like the hard disk, RAM, and the configura-tion of the many onboard subsystems. CMOS (ComplementaryMetal Oxide Semiconductor) refers to the chip on which the BIOSinstructions are stored. CMOS is the name of the technologybehind the chip that stores the BIOS. Present-day CMOS is techni-cally called EEPROM for Electronically Erasable ProgrammableRead-only Memory. These can be rewritten to, and this allows theBIOS instructions of a motherboard to be updated when required.

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Screenshot 3: Universal AGP slot.jpeg

Screenshot 4: AGP pro slot.jpeg

Screenshot 5: cmos chip.jpeg

The process of updating the BIOS instructions is called Flashing.

1.1.4 ChipsetRefers to a set, usually a pair, ofmicroprocessors that are pres-ent on the motherboard, andwhich controls the communi-cation between every compo-nent of the system - the CPU,the RAM, the expansion cards,and other peripherals pluggedinto the system.

The CPU has garnered allthe attention among computerusers, but the system's per-formance is just as much deter-mined by the much-ignoredChipset. The Chipset usuallycomprises the Northbridge andthe Southbridge. The namesare derived from the relativeposition of the microproces-sors with respect to the CPU. The chip closer to the CPU is calledthe Northbridge, and the one placed further away is referred to asthe Southbridge. The Northbridge has traditionally controlled thecommunication of the CPU with the rest of the system, namely thememory, the graphics subsystem (either onboard graphics or thegraphic card(s)), and the Southbridge. The Southbridge is tradi-tionally involved with controlling the communication betweenthe Northbridge and the peripherals, namely expansion cards notplugged into the graphics slot like the sound card and internalmodem, storage devices like the hard disks and optical drives, andthe ports - COM, USB, etc.

Exceptions to the traditional roles exist in the form of thechipsets for the AMD Athlon 64 series of processors, since the RAM

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northbridge near cpu southbridgebelow PCIe slot copy copy.TIF

controller has been included in the CPU itself; the Northbridge isno longer burdened with this task.

1.1.5 Display portThe 15-pin, mini DB 15 port, also calledthe VGA / Display port is used to connectan analogue monitor. With LCD monitorsbecoming popular, the DVI (Digital VideoInterface) port is also frequently seen.

1.1.6 Expansion slotsEarlier motherboards rarelyoffered additional functional-ity besides offering a place forthe CPU and RAM to beplugged in. The capability ofthe system had to be "expand-ed" with the use of externalcards that carried the addi-tional circuitry to fulfil thefunction. Additional circuitry usually included hard disk con-trollers, display adapters, sound system, etc., all of which arenowadays present "onboard" - referring to the inclusion of all thiscircuitry on the motherboard. Today, expansion slots on mother-boards are mostly PCI, PCIE, and AGP. A couple of rarely-used slotsare CNR (Communications and Networking Riser) and AMR (AudioModem Riser). These special slots were designed to incorporate theinterfaces for networking and audio devices; they did not containthe processing circuitry, andmerely acted as a channel.The processing was done bythe host CPU.

1.1.7 FireWire portFireWire ports are not as com-mon as USB, but do make anoccasional appearance on the

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VGA on Top, DVI below

AMR slot

AMR port

back panel. FireWire exists in two versions: FireWire 400, whichoffers a maximum data transfer rate of 400 Mbps, and FireWire800, which offers double that.

1.1.8 Form FactorThis is a name todenote the specifica-tions of a mother-board - like dimen-sions, power supplytype, location ofmounting holes, num-ber of ports on theback panel, etc. Themost commonly-usedmotherboards are ofthe ATX or Micro ATXform factor, which areused for Desktop sys-tems. An ATX(Advanced Technology Extended) motherboard is 12" x 9.6" in size,and supports the most number of expansion slots. Micro ATX isshorter than ATX, at 9.6" x 9.6", and was created to reduce total cost.The original ATX specifications have been updated to include tech-nological improvements and reconcile the requirements of laterPCs. For example, the latest ATX form factor specification includesthe 24-pin power connector, which the original did not. There aremany other form factors that cater to different PC designs: BTX,ITX, mini ITX, FTX, and more. VIA, a computer component manu-facturer that focuses on power efficiency, has been creating miniITX motherboards, which include all the functionality of the larg-er motherboards. With all important functions - video, audio, USB,and LAN - on board the motherboard, there is need for only one PCIslot and a RAM slot, besides a socket for the CPU, usually a VIAprocessor that consumes less than 5 watts. Such systems are idealfor use in situations where the workload is low and where the sys-tems need to be left running - like downloading very large files.

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A mini ITX motherboard

1.1.9 JumpersThese refer to theopen contacts onthe motherboardthat can be used toconfigure differentsettings of theboard. With time,the number ofjumpers has comedown, with most ofits functionality shifted to the CMOS / BIOS. Still, many mother-boards today do have one set of jumpers, which is used to reset theBIOS settings.

1.1.10 LAN portRJ-45, or the LAN port, allows the PC to be connected to a network,whether to a LAN or to the Internet via a broadband modem.

1.1.11 Parallel portThe DB 25 or Parallel port is the traditional port for older printers.These are rarely seen today.

1.1.12 PCB (Printed Circuit Board)The foundation of every electronic device is the board on whichevery component is connected. The PCB consists of minute con-ductors, usually of copper, seen as fine lines criss-crossing the sur-face, mounted on an insulated substrate. The minute pathwaysactually carry data signals or power between the various compo-nents that are eventually soldered on the PCB. PCBs come in vari-ous sizes and shapes, and besides the motherboard, are also seenin expansion cards (sound cards, graphics cards, etc.) and RAMmodules.

1.1.13 PCIPeripheral Component Interconnect is still widely seen in mother-boards, though it is older than AGP. The wide availability of PCI

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Jumpers

cards is one reason for this. This bus is 32 bits wide and operatesat 33 MHz, and has a maximum data transfer speed of 132Megabytes per second. This bandwidth is divided between all slotsand also the storage devices, like the hard disks.

1.1.14 PCIE (PCI-Express)PCI-Express is the latest type of expansion slot. Unlike the AGP andPCI buses which transfer data in a parallel fashion, PCIE offers seri-al data transfer. It is designed to be a point-to-point bus, and so itis not shared by other components. The bus is implemented as apair, with two lanes per bus. So it can act in full duplex mode,meaning that data can be simultaneously sent and received overdifferent lanes at full speed. It is also modular, in that the numberof PCIE lanes can be increased or decreased based on the need ofthe device. So a PCIE x16 slot that has 16 lanes (8 lanes each for car-rying data in one direction) can be used for graphics cards, whilea slower PCIE x2 slot can be used for less demanding componentslike modems and sound cards. Each PCI-Express lane can transfer2 Gigabits of data per second, which translates to 250 Megabytesper second.

1.1.15 PortsEvery motherboard offers a plethora of ports on its back panel.The most commonly seen ports on today's PCs are PS2, USB, VGA,LAN, Serial, and Audio Sockets.

1.1.16 PS2 portThe PS2 port is used to connect PS2-compatible keyboard andmouse. The violet-coloured port is usually for the keyboard, andthe green one is for the mouse.

1.1.17 RAM slotsThese refer to the interface to connect RAM modules. Memory isorganised in the form of banks, with one or more slots constitut-ing a bank. Each bank has a dedicated channel to the memory con-troller. Many motherboards, thanks to their Northbridges, imple-ment a dual-channel RAM mode, wherein the effective bandwidth

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of the bus is doubled. To use the memory in dual-channel mode,one slot in each bank needs to be fitted with RAM modules thatare similar in all respects.

1.1.18 Serial portDB 9 or Serial port is a 9-pin port that transfers data serially. It isincreasingly being left out from the back panel in favour of fasterports like USB. It is used today mostly for external modems.

1.1.19 SocketThe motherboardcarries the interfaceto connect the CPU.This is referred to asa Socket. There aremany socket types,with no clear nam-ing scheme, thoughmost are namedafter the number ofpin sockets they con-tain. The latest IntelCPUs require aSocket 775 interface,while the latest AMD processors require a Socket AM2 interface.Some older CPUs like the Pentium 2 used a slot-like interface,called Slot 1.

1.1.20 USB portsUSB ports are ubiquitous, with many newer motherboards offer-ing up to 10 USB connections. USB is available in two common ver-sions - version 1.1, which has a maximum data transfer rate of 12Megabits per second, and version 2, which tops out at 480Megabits per second. Besides speed, USB also allows up to 116 com-patible devices to be connected in a daisy-chain into a single port,and it also supports hot-swapping (the system would detect thenewly-connected device without requiring a restart).

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Screenshot 12: Socket 775.jpeg

1.2 RAM

RAM is short for Random Access Memory. In common parlance,RAM refers to system memory, the temporary storage area thatholds all the data that the CPU is working on. All data thatrequires processing by the CPU and the results of the processingare first stored in the system memory.

RAM, per se, refers to the type of storage medium that allowsany data stored within to be directly accessed without having toaccess the preceding data (the latter mode being called sequentialaccess).

System memory is volatile, which means that the stored datais lost when the device is powered down.

1.2.1 CASTo be able to access data from a particular storage area in RAM, theRAS and CAS procedures are needed to provide the address of thestorage area. The RAM is organised as an array of storage areas.Each storage area can therefore be uniquely identified by the num-ber of the row and the number of the column that intersect at thatposition. Row Access Strobe (RAS) is the process of identifying therow from which data needs to be read. This step precedes CAS.Column Access Strobe is the process of identifying the columnfrom which data is to be accessed.

1.2.2 CAS LatencyRefers to the delay between the CAS and the arrival of the datafrom the RAM. It is an indicator of the speed of the memory, andis expressed in the number of clock cycles: a CAS Latency of 3means that three clock cycles are needed after the CAS for data tobe produced by the RAM.

1.2.3 DDR SDRAMDouble Data Rate SDRAM was an evolutionary improvement overSDRAM. It allowed data to be transferred twice during every cycle.

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This effectively doubled the frequency of the memory; DDR 266memory actually works at 133 MHz. It is important to note thatthe term is "DDR 266" and not "DDR 266 MHz." Another mode ofnotation is by referring to the peak data transfer speeds. So a DDR266 module is also referred to as PC 2100, since it can transfer 2100Megabytes per second. DDR modules have 184 contacts, and arenot backward-compatible.

1.2.4 DDR2 SDRAMAn evolution of DDRSDRAM, DDR2allows four datatransfers per clockcycle, by clockingthe internal bus attwice the speed ofthe memory clock. Therefore the effective frequency of the mem-ory becomes 4 times its actual frequency. A DDR2 800 moduleoperates at 200 MHz. As in the case of DDR SDRAM, the alternatenotation relying on the maximum data transfer speeds is alsoused. PC2 3200 refers to DDR2 400. A DDR2 module has 240 con-tacts, and is not backward-compatible.

1.2.5 DDR3 SDRAMThis is the latest iter-ation of SDRAM, andincreases the inter-nal bus speed to 8times the memoryclock, effectivelyoperating at 8 timesthe frequency. DDR3 800 operates at 100 MHz and is also referredto as PC3 6400. DDR3 is still a cutting-edge technology, and is sup-ported by very few motherboards and CPUs. DDR3 modules alsohave 240 pins, but they are keyed differently, so they cannot beinserted into a DDR2 slot.

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Screenshot 13: DDR module.jpeg

Screenshot 15: DDR3 module.jpeg

1.2.6 DIMMDual Inline Memory Module refers to the package in which RAM isavailable. Unlike the earlier and now obsolete SIMM (Single InlineMemory Module), a DIMM has contacts on both sides of the module.

1.2.7 DRAMDynamic RAM refers to volatile RAM that is constantly refreshedto prevent stored contents from being lost. All modern RAM is ofthis type, though there have been improvements. Data is stored inthe form of rows and columns, with each storage area in RAM hav-ing a unique address that is a combination of the row and columnnumber. DRAM was available in different types like SDRAM, EDO(Extended Data Out) RAM, FP (Fast Paging) RAM, and more, all ofwhich are now obsolete except for SDRAM.

1.2.8 ECC RAMAn Error Correction Code (ECC) RAM module is a special type ofmodule that includes additional components to verify the integri-ty of data stored in or transferred by system RAM. This is neededin critical systems that require high levels of data integrity, likeservers.

1.2.9 RAS to CAS delayThis is the number of clock cycles that intervene between the iden-tification of the row with the RAS and the start of launching theCAS. This is displayed as "tRCD" in the BIOS.

1.2.10 RAS Precharge TimeThis is the number of cycles that are needed to refresh the RASafter the previous access before it can be used for a new access.

1.2.11 RDRAMRAMBUS Direct RAM was based on a technology developed byRAMBUS. Unlike SDRAM, it used a serial mode of data transfer,and though the technology was considered superior to DDRSDRAM, it's expensiveness made it unpopular. RDRAM modulesare called RIMMs.

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1.2.12 Registered RAM / Buffered RAMThis type of RAM module had additional storage areas - calledbuffers or registers - where the data is stored temporarily andchecked for data integrity before being transferred. Similar in useto ECC RAM, though using a different method, this type of RAM isneeded in servers, which require high levels of data integrity.

1.2.13 SD RAMSynchronous Dynamic RAM was an improved version of DRAMthat synchronised all its functions to a single frequency, usuallythe system's FSB frequency. The frequency refers to the rate atwhich the RAM would perform an action, namely refreshing, read-ing, or storing. SD RAM is available in various frequencies, withthe fastest modules capable of running at 266 MHz (high perform-ance modules, targeted at enthusiasts, which perform at higherfrequencies, are also available). SD RAM modules have 168 con-tacts. After the release of DDR SDRAM, the original SDRAM beganto be referred to as SDR SDRAM (Single Data Rate SDRAM).

1.3 Processor

1.3.1 32-bit / 64-bit CPU"32/64-bit" refers to the width of the address bus and registers usedby the CPU core. A 64-bit CPU has a 64-bit wide address bus and 64-bit wide registers. CPUs access data in the RAM by using theaddress bus. The breadth of the bus influences the amount of RAMthat can be addressed. A 32-bit bus allows a maximum of 4 GB ofRAM to be accessed. A 64-bit CPU, obviously, allows for more RAMto be used - about 16 exabytes (1 exabyte = 1,000,000,000 gigabytes,approximately). A 64-bit register can store 64 bits of data simulta-neously. To fully utilise a 64-bit CPU, the operating system andapplication need to support the 64-bit mode of operation.

1.3.2 BGAA Ball Grid Array (BGA) package is similar to a PGA package, exceptthat the role of the pins is taken over by small balls of conductive

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material. The advantageis that unlike pins, theconductors are not easi-ly bent. Unfortunately,BGA CPUs are solderedright onto the mother-board, and users cannotreplace them. This formof packaging is seen insome embedded CPUslike those from VIA.

1.3.3 Cache memoryAll CPUs presently made have two components in their die - theprocessing core and some memory. The memory is used to storefrequently-used data so that the CPU doesn't have to wait for thedata to be fetched from other, slower storage areas like the systemRAM or hard disk. This temporary storage is referred to as thecache. Unlike system RAM, cache is made of more expensive StaticRAM, which does not require refreshing. There can be multiplecaches per CPU. The cache that is closest to the CPU core is calledthe Level 1 cache, and is most frequently accessed by the CPU. Thesubordinate cache, called the Level 2 cache, is approached only ifthe data is not available in the L1 cache. Some high-end CPUs alsosport a Level 3 cache. Cache sizes tend to increase with theirLevels, with L1 caches being smaller than L2. In current CPUs, theL1 cache tops out at 128 KB per core, while the L2 cache tops outat 8 MB per core.

1.3.4 Cool 'n' Quiet / Speed StepThese refer to the power management schemes used by AMD andIntel respectively. This allows the CPU to conserve energy by alter-ing its speed according to the processing load. At slower speeds,the power consumption is decreased.

1.3.5 Die sizeA Die refers to the block of silica that contains the core logic of a

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Screenshot 16: BGA chip.jpeg

CPU. The die size is affected by the fabrication process and thenumber of transistors included within.

1.3.6 Fabrication processThis term is used to refer to the smallest distance between twocomponents in the CPU. All CPUs contain miniature circuitsetched on a silicon chip. The latest Intel CPUs use a 45-nanometreprocess.

1.3.7 FPUFloating Point Unit; a sub-unit of the CPU core. The CPU is madeup of different functional sub-units. There is the ALU (Arithmeticand Logical Unit), the FPU, Registers (temporary storage areas), andthe caches. The CPU Core refers to all components of the CPUexcept the caches; it forms the area that is responsible for theactual computation.

1.3.8 FSBThe Front Side Bus is the data channel between the CPU and thesystem RAM. In turn, the Back Side Bus refers to the link betweenthe CPU and the cache memory within the CPU die itself. The FSBfrequency is the speed at which the bus operates, and is an indi-cator of the number of times the CPU interacts with the rest of thesystem. Usually, the CPU itself works much faster than the FSB (seeMultiplier).

1.3.9 LGA A Land Grid Array package is the latest form of packaging, seen inIntel's latest CPUs. This form of package does away with pins orother projections, and offers sockets only. The pins are present onthe socket in the motherboard.

1.3.10 Multi-core CPUsMany present CPUs are multi-core, meaning that there exist morethan one computational unit on the same CPU. This allows for bet-ter performance when dealing with several jobs simultaneously.Both the major manufacturers offer quad-core CPUs.

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1.3.11 MultiplierOriginally, all the components on a system operated at the samefrequency. But with improvements in technology, the rest of thesystem became a bottleneck to the CPU achieving its full potential.This problem was solved by allowing the CPU to operate multiplecycles for every cycle that the system operated. This factor is calledthe Multiplier. Earlier it was possible for the user to set the multi-plier using switches on the motherboard, but now, except for thehigh-end CPUs, most CPUs come with a set multiplier.

1.3.12 Package typesEvery CPU is packaged to ensure that its core components are pro-tected, while allowing connection with the motherboard. Packagetypes seen in current CPUs include PGA, BGA, and LGA.

1.3.13 PGAShort for Pin Grid Array, this type of packaging has a grid of con-ducting pins projecting from the package, which connect into thesocket. PGA is available in different formats like FC PGA forFlipped Chip PGA, mPGA for micro PGA, and OPGA or organic PGA.AMD CPUs use this form of package.

1.3.14 PipeliningThis refers to the internal data processing pathways of a CPU. TheCPU processes data through different stages, like Fetch, Decode,Execute, and Store. By Pipelining, it becomes possible to performthese stages independently and on different bits of data. Thisallows for more efficient use of CPU cycles.

Modern CPUs have increased the number of stages in thepipeline, and also use advanced techniques like branch prediction,which is used to estimate the possible outcome of an if/else condi-tion, to ensure that every stage of the pipeline is utilised.

The performance of the CPU is greatly influenced by the way itimplements pipelining.

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1.3.15 HSFShort for Heat Sink Fanunit, this refers to thealuminium block andfan unit placed over theCPU to aid in dissipationof heat. While most stockHSF units are made ofaluminium and use afan, fancier cooling solu-tions made of copper andusing liquid coolants arealso available.

1.3.16 OverclockingOverclocking refers to the art of making a computer component per-form at levels exceeding those set by the manufacturer. Componentslike the CPU, RAM, and graphics cards can be overclocked.

1.3.17 HyperThreadingThis was a technology used by Intel to improve CPU utilisation bysplitting a processing workload into parallel threads. Thanks toHyperThreading, the CPU appeared to the OS as multi-core. Tomake use of this feature, it was essential that the OS and mother-board supported it.

1.3.18 TDPThermal Design Profile refers to the average energy (expressed inwatts) in the form of heat that the HSF has to dissipate from theCPU. This can be taken as a rule-of-thumb measure of the energyconsumed by the CPU.

1.3.19 Transistor countThis refers to the number of transistors included in the CPU core.The transistor count is influenced not just by the complexity ofthe core, but also the size of the on-die cache. The transistor countof a Intel Core 2 Duo CPU with a 2 MB cache is 151.6 million.

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Screenshot 17: Heatsink Fan unit.jpeg

1.4 Code-names

CPU manufacturers use a code-name for a CPU during its develop-ment. Once the product is launched, it gets a formal name, whichis the name of the current product family. Usually, a new code-name points to improvements in the core, so even if all CPUs inthe product family carry the same name, a knowledge of theircode names can help identify internal differences. For example,Intel Core 2 Duo CPUs have different internal properties corre-sponding to different code-names.

The following table lists some dual-core CPU code-names andtheir specifications.

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XxxxMMffrr..

Intel

AMD

CCPPUU FFaammiillyy

Core 2 Duo

PentiumDual Core

Pentium D

Athlon 64X2

CCooddee--nnaammee

Conroe

Allendale

Allendale (Same coreas used inCore 2 Duo,but with halfthe cachedisabled.)

Smithfield

Presler

Manchester

Toledo

Windsor

Brisbane

PPrroocceessssSSiizzee

65 nm

65 nm

65 nm

90 nm

65 nm

90

90

90

65

LL22 CCaacchhee SSiizzee

2 MB or 4 MB

2 MB

1 MB

1MB per core

2 MBper Core

256 MB or 512KB per core

512 KB or1 MB per core

512 KB or1 MB per core

512 KB percore

FFSSBB

1066 or1333

800 or1066

800

533 or 800

800

1000 MHz*

1000 MHz*

1000 MHz*

1000MHz

SSoocckkeett

Socket775

Socket775

Socket775

Socket775

Socket775

Socket939

Socket939

SocketAM2

SocketAM2

1.4.1 In The PipelineA few innovations expected in 2008

1. AMD's quad-core processor for the Desktop, Phenom (not"Athlon X4"), was released towards the end of 2007. One canexpect to see larger number of these CPUs entering the market.

2. Intel's "true" quad-core processor for the Desktop market,presently code-named Penryn, featuring four cores on the samedie, is expected in 2008. (Intel's present Core 2 Quad processorsare not native quad-core; rather, they fuse two Core 2 Duoprocessors.) Penryn is also the first CPU to use the 45nm fabri-cation process, the smallest in the industry. Penryn-based CPUshave already been released for the server market, under theXeon label.

3. DDR 3 SDRAM, presently marketed only by a few high-end mem-ory manufacturers, and supported only by Intel's P35 chipset,can be expected to gain broader market acceptance.

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Here we talk about hard disks, optical drives and disks,and Flash storage—things you interact with on a dailybasis. You’ll therefore notice that most of the following

terms are at least somewhat familiar.

Storage

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2.1 The Hard Disk

2.1.1 Access TimeReading data from or writing data to a hard disk involves the rota-tion of the spindle to bring the required sector under the read/writehead, and the motion of the read / write head to the desired track onthe platter. The access time is the sum of the time taken for these.

2.1.2 Active PartitionThis is the partition that has been marked in the MasterPartition Table as containing the boot information. Only one par-tition can be marked as active, though more than one can con-tain the boot information.

2.1.3 ATA / IDEThe ATA (Advanced Technology Attachment) specification dealswith the interface between the motherboard and hard disks thathave integrated circuitry. This standard is also referred to as IDE(or Integrated Drive Electronics). Earlier, the hard disk controllerhad to be separately plugged into an expansion slot, with cablesrunning to the hard disk from the controller. ATA has many ver-sions, which have increasingly improved the features and speedsof the connection. ATA 2 is also called Extended IDE (EIDE) becauseit introduced support for large drives by using the LBA namingscheme. ATA 6 is the last version of ATA, and is also referred to asATA/133, which denotes the maximum data rate for the interface—133 Megabytes per second.

2.1.4 ATAPIAdvanced Technology Attachment Packet Interface is a protocolthat that allows optical drives to be connected through PATAcables to IDE controllers. This forms part of the ATA version 4 spec-ifications.

2.1.5 Bad SectorBad sectors are areas on a hard disk that are physically damaged.The data present in these areas cannot be read with normal soft-

ware, and no data can be stored there. All hard disks, includingnew ones, have bad sectors, which are a normal occurrence duringthe manufacturing process. The locations of the bad sectors arerecorded by the hard disk circuitry, ensuring that they are avoid-ed. However, bad sectors can also form during use, either as aresult of improper shutdowns—causing the read / write head tophysically scratch the recording surface—or due to normal wearand tear. Newly-developed bad sectors can also be recorded toensure that they are not accessed the next time. This can be doneby performing a “thorough” format of the drive.

2.1.6 Boot SectorEvery partition in a hard disk contains critical data in the first sec-tor, carrying information about loading the operating system. Thisfirst sector is called the boot sector. Any partition containing rele-vant information in the boot sector is termed bootable, and iscalled the Boot Partition.

2.1.7 BPIBits Per Inch refers to the number of bits stored per linear inch ofa track.

2.1.8 CacheCache is the memory incorporated in the hard disk that stores fre-quently-accessed data. This saves use of the read/write head, thusextending its life, besides, obviously, improving performance. A 2MB cache is common in most hard drives, with the highest being16 MB in the latest, large-capacity drives. The maximum transferspeeds of the interface that is mentioned in the drive specifica-tions refers to the time it takes for the cache to send the data.

2.1.9 CHSCylinder Head Sector is a naming scheme used to uniquely addressevery storage area or sector in a hard disk. Each sector can beuniquely identified, based on the number of the Cylinder, the read/ write head operating on that platter, and the number of that sec-tor in that cylinder.

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2.1.10 ClusterA cluster refers to the group of sectors that are manipulated as aunit. Depending on the filesystem and the size of the partition, thenumber of sectors that form a cluster changes. From the operatingsystem’s point of view, the cluster is the smallest storage unit.

2.1.11 CylindersA platter is made up of concentric tracks along which the read /write head stores data. The tracks are numbered. A cylinder refers tothe same-numbered tracks of all the platters, since, theoretically,they form a cylinder.

2.1.12 DMA/UDMADirect Memory Access / Ultra Direct Memory Access refers to atechnology that allows a hard disk to manage data transfer with-out the aid of the CPU. This speeds up data transfers, while alsoleaving the CPU to perform other tasks. DMA / UDMA have gonethrough many iterations, the latest being UDMA 6, which offerstransfer speeds of 133 Megabytes per second. DMA / UDMAmodes are specified in the ATA standard. To achieve speedsabove 33 Megabytes per second, as envisaged in UDMA3, a spe-cial 80-pin conductor cable is needed to reduce the interferencethat occurs between two data-carrying channels. Though thedata is transferred using only 40 pins, the remaining pins areneeded to ground interference created during the data transfer.

2.1.13 eSATAExternal SATA is an interface that allows standalone SATA drivesto be connected from outside the system. Since the SATA speedsextend to eSATA devices, eSATA offers the highest data transferrates among allinterfaces—namely,USB 2.0 andFireWire—at 3Gigabits per sec-ond (in case ofSATA 2).

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An eSATA plug The eSATA connector

2.1.14 Extended PartitionAn Extended Partition refers to the entry in the Master PartitionTable that points to the location of the Extended Partition table.The Extended Partition is not assigned any letter.

2.1.15 Form FactorHard disks come in different sizes to match the systems they areintended to be used in. The 3.5-inch hard disk is what is used inall Desktop PCs. The 2.5-inch hard disk is used in laptops. Someconsumer electronics products like the iPod use a 1.8-inch inter-nal hard disk.

2.1.16 FormattingFormatting is of two types—low-level and high-level. Low-levelformatting creates the tracks and sectors that are used to storedata. High-level formatting involves preparing the filesystemand creating a record of avoidable bad sectors in the partitions.All present hard disks are low-level-formatted by the manufac-turer, and the user only performs a high-level format. A high-level format can be performed in two ways: a Quick Format,which erases the existing file index and creates the desired filesystem, and a Thorough Format, which in addition also per-forms a bad sector scan.

2.1.17 GMRGiant Magneto Resistance is the phenomenon behind the tech-nology used by the read heads in modern drives to read the datastored on disk platters. The GMR effect is a property of thin filmsof certain materials that experience large changes in resistanceas a result of very small changes in magnetic field. This effectallows the information about changes in magnetic fields to bedeciphered by detecting changes in resistance. And since evenminute changes in magnetic field can be detected, these magne-tised spots can be more closely packed, leading to greater storagearea on a platter of the same size. The 2007 Nobel Prize forPhysics was awarded to the discoverers of this effect—Albert Fertand Peter Grünberg.

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2.1.18 HeadsRead / write heads refer to the main reading and writing appara-tus in a hard disk. The Read head contains thin films that displaythe GMR effect. The Write head is usually made of an electromag-netic substance that gets magnetised when electricity is passed toit, thus magnetising the spot below it.

2.1.19 Hybrid DrivesThese are hard drives that include both rotating disks as well asFlash memory based storage. This is an attempt to combine thebenefits of the two types of storage media: the inexpensiveness ofrotating platters and the non-volatility of Flash memory. The Flashmemory component in a hybrid drive is merely a temporary stor-age area; the data is finally written onto the disk. Like the cache inregular hard drives, the Flash memory improves performance, andsince unlike cache memory the data is not lost when powereddown, startup time is reduced since there is no longer the need towait for the disks to rev up.

2.1.20 Landing ZoneDuring normal operation, the read/write heads levitate over theplatter surface thanks to the air cushion created by the rotation.When powered down, the heads are brought to rest over an areaon the platter where data is not stored. This is the landing zone.

2.1.21 LBALogical Block Addressing refers to the scheme used by modernhard disks to overcome the bottlenecks presented by older BIOSlimitations that do not detect large-capacity hard disks. LBA allo-cates a unique number to each sector. The hard disk circuitrytranslates this into the respective CHS values, which is compre-hended by the BIOS.

2.1.22 Logical DrivesThis refers to the partitions created in an Extended Partition. A max-imum of 24 logical drives can be created, since each drive needs tobe lettered, and letters A and B are reserved for floppy disks.

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2.1.23 Master / SlaveSince a PATA controller allows two devices to be connected to thesame channel, one has to be designated the “Master” and the otherthe “Slave” to avoid data being wrongly routed. This is just a con-vention—the drives could as well be termed “first” and “second.”

2.1.24 MBRThe Master Boot Record resides in the first sector of the hard disk.This contains critical information like the Master Partition Tableand the information about the active partition.

2.1.25 MTBFMean Time Before Failure is the average life of the hard diskexpressed in hours of usage.

2.1.26 NCQNative Command Queuing is a feature of SATA hard drives. Thisallows read / write requests made to the hard disk to be re-orderedto use the movements of the internal components more efficient-ly, leading to lower waiting periods.

2.1.27 Partition TableA Partition is a logical subdivision of a hard disk into smallerchunks. The partition table is the record of the partitions on ahard disk. There are two types of partition tables. The MasterPartition Table forms part of the MBR, and can carry details of onlyfour partitions. The need for more than four partitions was met byallowing the creation of an Extended Partition Table, which couldcontain an unlimited number of partition entries (though the let-ters in the alphabet limits this number to 24). The Master PartitionTable contains a reference to the Extended Partition Table.

2.1.28 PATAThe original ATA standard had to be called PATA (for Parallel ATA)after the advent of Serial ATA for sake of differentiation. PATArefers to an interface used for connecting hard disk and opticaldrives to the system. It used the parallel mode of data transfer,

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which peaked at 133 Megabytes per second. Due to the proximityof the data carrying wires, interference was a major bottleneck togreater speeds. Each PATA channel can support two devices in aMaster / Slave configuration.

2.1.29 PIOProgrammed Input Output mode of data transfer is the mode ofdata transfer that requires the CPU’s intervention (in contrast toDMA and UDMA). Older optical drives still use this mode. There aremany versions of PIO mode, with the latest being version 4, whichoffers a maximum speed of 16.7 Megabytes per second.

2.1.30 PlatterThe surface on which data is stored in the form of magnetised andnon-magnetised regions is usually a glass or aluminium disk coat-ed with a magnetic substance. This disk is called a platter.

2.1.31 PMRPerpendicular Magnetic Recording is a improved method for stor-ing data on platters, allowing for greater areal density. Unlike thepresent method, also called Longitudinal Magnetic Recording,where the magnetised areas are laid out end to end, in PMR, theareas are arranged vertically, side by side, thus reducing the spacethey occupy.

2.1.32 Primary PartitionThis refers to the partition whose details are included in theMaster Partition table in the MBR. A maximum of four primarypartitions can exist in a hard disk.

2.1.33 RAIDRedundant Array of Independent (mistakenly called Inexpensivesometimes) Disks is a scheme that allows multiple hard disks to beused to create a single unit with features better than what wouldbe attained if they were not a unit. A “RAID controller” containsthe circuitry to manage the disks as a single unit. There are differ-ent RAID schemes. The most popular ones are RAID 0, 1, 0+1 and 5.

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RAID 0 allows Striping, a scheme where alternate blocks ofdata is written to different disks. This results in a direct doublingof the write / read speeds. The flip side is that if one of the disksfails, the entire data becomes inaccessible.

RAID 1 offers data redundancy by mirroring the data. In thisscheme, the same data is written to both disks. While there is noimprovement in performance, from the security standpoint, fail-ure in one disk will not result in downtime, since the same data ismirrored on the other disk(s). Both the above-mentioned schemesrequire at least two hard disks to function.

RAID 0 + 1 brings together the benefits of both the schemes,and obviously requires a minimum of four hard disks to function.RAID 5 allows striping, but also stores the parity information ofevery operation, which can be used to recover data in case of fail-ure. This scheme requires a minimum of three drives.

2.1.34 Rotation SpeedThis refers to the speed with which the spindle rotates. Naturally,the faster the disk rotates, the faster the data can be accessed andwritten or read. The fastest hard disks have a speed of 15000 rpm.Regular hard disks are available at 7200 rpm and 5400 rpm, withlaptop hard disks also available at 3500 rpm.

2.1.35 SATASerial Advanced Technology Attachment refers to the latest formof connection for storage devices like hard disks and optical drives.Data is transferred serially though the interface. The SATA stan-dard has two versions: SATA 1, which offers a maximum datatransfer of 1.5 Gigabits per second, and the later SATA 2, whichoffers data transfer speeds of up to 3 Gigabits per second. UnlikePATA, each SATA channel can connect to only one device.

2.1.1 SCSISmall Computer System Interface is a high-performance inter-face mostly used in server systems. It offers better data transfer

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speeds than PATA,and other advan-tages like “hots w a p p a b i l i t y , ”which refers to thecapacity to plug in additional storage devices without the needto restart the computer to get it detected, and the ability to con-nect up to 15 devices to a single channel. SCSI technology hasimproved over the years; the latest iteration is called Ultra 160SCSI, which offers a maximum data transfer rate of 160Megabytes per second.

2.1.36 SectorsA Sector is the smallest logical division of a track. It is usually 512bytes in size.

2.1.37 SMARTSelf Monitoring Analysis and Reporting Technology is a featureof all modern hard disks that allows a disk to predict its own fail-ure by monitoring various operating parameters. For example,an increase in operating temperature is indicative of increasedfriction, which could lead to failure of the drives. In such cases,a SMART drive will report a warning diagnostic message to theuser at boot time.

2.1.38 SpindleA hard disk is organised as one or many platters rotating on a cen-tral axis. This arrangement isthe spindle.

2.1.39 SSDSolid State Drives refer tothe new-generation drivesthat are built using Flashmemory technology. Theseoffer better power economyand data transfer speeds,

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A SCSI socket

Samsung’s SSD drive

and due to the absence of moving parts, are more sturdy andsilent. Since they are much more expensive than disk-based stor-age media, they are still niche products. The current maximumcapacity of an SSD is 64 GB, with larger disks coming soon.

2.1.40 TPITracks per inch refers to the number of tracks present per radialinch of a platter.

2.1.41 TracksData is stored in concentric paths on a platter; the concentricpaths are called tracks.

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2.2 Optical Drives

2.2.1 Blu-ray DiscBlu-ray Disc (BD) is a next-generation optical storage mediumdeveloped by Sony and others. It uses a blue-violet laser with 405nanometre wavelength, and offers 25 GB (single layer) 50 GB(dual layer) storage capacity. Blu-ray discs appear as BD-ROM(read-only, pre-manufactured), BD-R (recordable once), and BD-RE (recordable and erasable). The 1X data transfer speed for aBlu-ray drive is 4.5 Megabytes per second. The Blu-ray Disc for-mat is not compatible with the other next-generation opticalstorage medium, HD-DVD.

2.2.2 Bootable DiscOptical discs that can be used to start a system are termedbootable. Technically, these discs follow the El Torito extension ofthe ISO 9660 file format; any motherboard that is compatiblewith this standard recognises optical drives as a bootable device,and can pass on control to the optical drive to boot the system.Today, bootable optical disks are the norm; you won’t findbootable floppy disks except in a few rare cases.

2.2.3 BufferBuffer refers to the internal memory present in the drive wheredata is stored before being written to disc. A 2 MB buffer is com-mon in all drives.

2.2.4 Buffer Underrun ProtectionIf the buffer becomes depleted midway during a writing session,the media gets corrupted and unusable. Buffer UnderrunProtection refers to the techniques used by optical writing devicesto prevent the corruption. The writing is temporarily stoppedwhen the buffer is depleted, and resumed when it is filled again.The gap that results is small enough to be tolerated by CD readers,thus ensuring that the CD is not corrupted. Different manufac-turers use different names to refer to this technology—likePowerburn (Sony), Super Link (LG), etc.

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2.2.5 Burning / RecordingBurning refers to the process of recording data on to Recordablemedia. It is called burning since the heat of the laser beam causesthe dye to change from transparent to opaque. The opaque areasdo not reflect light as well as the transparent area, thus simulat-ing the behaviour of actual pits and lands.

2.2.6 CAVConstant Angular Velocity refers to the rotational characteristic ofthe drive. In CAV mode, the rpm remains the same, so data closerto the outer margins of the CD are read or written faster thanwhen present on the inner side. Most drives use this mode of oper-ation when dealing with data nearer to the inner margin, andswitch to CLV when closer to the outer margin (see next).

2.2.7 CLVConstant Linear Velocity drives do not have a fixed rpm, butchange this to allow the same length of track to be covered. This ismade possible by using a higher rpm when reading areas close tothe inner side, and using a lower rpm when reading data off theouter side.

2.2.8 CDThe Compact Disc was the first popular optical storage media.The result of a collaboration between Philips and Sony, its orig-inal use was for playback of audio recordings. CDs are availablein the following types based on the content they carry: CD A(Audio CD), Video CD (for video), Mixed Mode CD (Containingaudio and other data types), Data CD (containing all forms offiles), CD—I (CDs containing interactive content), and more.Based on their recording capability, we have CD-ROM (Read-only;all pre-manufactured CDs are of this type); CD-R (recordableonce); and CD-RW (read and write many times). The original CDdrive could read data at 150 Kilobytes per second, and every sub-sequent CD drive speed has been rated as a multiple of thisspeed. The laser used in a CD drive has a wavelength of 780nanometres. The rated storage capacity is 700 MB.

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2.2.9 Combo DriveThis is a drive that can read and write CDs and also read DVDs.

2.2.10 ConstructionAll optical media are prepared using the same procedure. The sub-strate is the clear plastic layer that forms the bulk of the disc. A thinlayer of dye is placed above the plastic. This is where the laser recordsdata in the form of burned or clear spots. The dye, which is com-monly made of Cyanine or a compound thereof, changes its opticalproperties under the laser beam. In the case of pre-manufacturedCDs, the pattern of pits and lands are stamped on the substrate itself.A reflective film, usually made of silver or gold, comes next. Finally,a protective acrylic coat is applied. Additionally, a layer for labellingpurposes is added. In case of dual-layer media, there are two layers ofdye with a layer of semi-reflective material in between them.

2.2.11 DAOThe Disk-at-Once mode of writing refers to when all tracks arerecorded without stopping the laser; the disc is finalised at theend and no further data can be added. In a DAO writing, there isonly one Lead-in and Lead-out.

2.2.12 DVDThe Digital Versatile Disc was created to fulfil the need for storageof high-quality video data. Two camps existed in the DVD technol-ogy arena: Philips and Sony were developing a new technology forstorage of high-quality video, while simultaneously, Toshiba,Hitachi, and others were involved in developing a parallel tech-nology that was incompatible with Sony’s technology. The twocamps agreed to collaborate and the result was the DVD, in 1995.

DVDs can store up to six times as much as a CD, at 4.7 GB (ifyou consider a Kilobyte as 1,000 bytes), while using a disk of thesame size. This was possible by using a laser of a smaller wave-length—630 nanometres—and reducing the width of the tracksand the distance between them. The original DVD drive had a datatransfer rate of 1.5 Megabytes per second.

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Based on the number of recording surfaces, DVD is available assingle side—single layer (also referred to as DVD5), single side—dual layer (DVD9), double side—single layer (DVD 10), and doubleside—dual layer (DVD 18). Dual-layer DVDs effectively doubled thestorage capacity to 8.5 gigabytes (per side).

Based on the recording capabilities, DVDs can be categorisedinto DVD-ROM (read-only, usually the format for pre-manufac-tured DVDs), DVD-RAM (Random Access Memory, allowing read-ing and writing), DVD-R, and DVD+R (one-time recordable),DVD+RW & DVD-RW (rewriteable). The “+” and “-” in the nomen-clature refer to the two incompatible formats offering the samefeatures. Drives that are labelled as “super multi” are capable ofplaying all formats.

2.2.13 ErasingRewriteable media can be reused by erasing the existing contents.Erasing involves overwriting all areas on the disk with the samedata. Erasing can be of two types: Quick Erase, where only theTable of Contents is erased, and Full Erase, where every sector onthe disc is filled with the same pattern.

2.2.14 EVDEnhanced Versatile Disc is a Chinese government-backed record-ing media for storing DVD video content. The need for this formatarose since the licensing fees to be paid for DVD players to foreigncompanies were high. EVD is free from content protection tech-niques, and is (initially) available only in the read-only form.

2.2.15 FVDForward Versatile Disc is a technology promoted by the Taiwanesegovernment to store High Definition video content. It uses theMicrosoft Windows Media Video (WMV9) and Audio (WMA9)codecs for compressing the audio/video streams. It uses normalDVDs, but increases the track count to allow storage of 5.5 GB ofdata on a single layer, with the capability to have three layers onone side, giving a total storage capacity of 15 GB.

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2.2.16 HD-DVD / AODHigh-Definition DVD is a new format of optical storage that is pri-marily intended to store High Definition video data. It was alsocalled Advanced Optical Disk. It is incompatible with Blu-ray disctechnology. It uses a blue violet laser with wavelength of 405nanometres. It is capable of storing 15 gigabytes of data on a sin-gle layer and 30 GB in dual-layer. HD-DVD disks appear in the fol-lowing types: HD-DVD RAM (read and write), HD-DVD ROM (read-only; all pre-manufactured discs), HD-DVD—R (read once), and HD-DVD—RW (read and write ). The data transfer rate of the first HD-DVD drive was 4.36 Megabytes per second.

2.2.17 ISO 9660One comes across this term when writing a CD. ISO 9660 is a fileformat for CDs. It was necessary to create a standard file systemsince competing operating systems created CDs that were notcompatible with other operating systems. The ISO 9660 file for-mat is an old format and is used in CDs since it guarantees max-imum compatibility with standalone CD players. This standardformat has been extended to increase its functionality. The Jolietextension allows the use of filenames larger than eight lettersand containing non-ASCII characters. The El Torito extensionallowed optical media to be made bootable. ISO 9660 is beingreplaced by UDF.

2.2.18 LaserThe optical drive uses a laser to read from and record data ontooptical discs. A laser-emitting diode is used to create the laserbeam. In drives like the combo drive, two laser diodes are used,and depending on the nature of the media, the appropriate laseris used.

2.2.9 Lead-inThis refers to the additional information that identifies the datawritten in a session. The Lead-in contains a Table of Contents,which has a list of files written in the session.

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2.2.20 Lead-outThis refers to the additional information written after the actualdata to inform the drive about the completion of the session.Without this information, the device would continue to search thedisc for additional data, as happens when a session is interrupted.

2.2.21 OverburningEvery writeable optical disc has a maximum stated capacity.Overburning refers to the practice of writing more data than thestated capacity. In some cases, the disc has the capacity to accom-modate overhead information, and this area can be written to byoverburning. The procedure can, however, be risky, since it couldrender the disc and/or the drive unusable.

2.2.22 Packet WritingThis is a specialised way of writing onto optical media that allowsdata to be erased and written to without the limitations imposedby normal optical media writing. Unlike normal writing, wherewriting can be performed only in sessions and deleting a sessiondoes not free space unless the drive is erased, packet writingallows data to be written and erased from optical media just as inthe case of floppy disks. To be able to use packet writing, the driveshould be compatible with the Mount Rainier specifications of theUDF file format, and the media needs to be specially formattedunder the Mount Rainier format.

2.2.23 Pits and LandsIn pre-recorded optical drives, datais stored in the form of depressionson the track. The depressions orpits, and the non-pitted area orLand are interpreted as binary dig-its (0s and 1s).

2.2.24 Read / Write HeadThe Read / Write head of an optical drive consists of a laser emittingdiode, a lens, and an optical sensor. The lens focuses the laser beam

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Pits and lands litter CD surfaces

created by the diode onto the media. The lens is connected withsprings that allow small changes to be made to accommodate forsmall differences in the disc surface. The laser is reflected by thereflective layer, but based on the presence of a Land or Pit (or trans-parent or opaque area) on the media, the laser is reflected backinto the sensor accurately, or is diffused. This difference in intensi-ty of the reflected light is interpreted as binary digits (0s or 1s).

2.2.25 SAOThe Session at Once mode of writing, also called Multisession writ-ing, writes data to the medium in the form of sessions, completewith the Lead-in and Lead-out. This allows the data on an incom-pletely-written disc to be read.

2.2.26 SectorsTracks on a optical media are subdivided into sectors, which arethe smallest storage unit of the medium. In CD ROMs, a sector con-tains 2352 bytes, while in a DVD, the sector is 2048 bytes long.

2.2.27 SessionA session refers to the basic unit of data written to a disc. A sessionconsists of a Lead-in, the actual data, and a Lead-out.

2.2.28 Speed notationThe original “X” that is used to denote reading and writing speedsin optical drives of all types refers to the speed of the first drive ofthat type. So a 52X CD drive can read or write data 52 times fasterthan the original CD drive, which means at about 150 x 52, or7800, Kilobytes per second. The notation seen on optical drivesrefers to the speeds during different operations. For example, aCD-Writer with the 52X24X40X notation can read CDs at 52X,erase CDs at 24X, and write CDs at 40X.

2.2.29 StampingOptical discs are manufactured in bulk by first creating a die thatcontains the pattern of pits and lands that represent the data. Thispattern is then transferred to the disc by “stamping” it onto the die.

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2.2.30 StandardsOptical media are governed by standards that are referred to as“Books,” like The Orange Book, The White Book, The Blue Book, etc.The Red Book, the original standard, specifies the requirements forAudio CDs. The White Book specifies the requirements for Video CDs.

2.2.31 TAOThe Track-at-Once mode of writing stops the writing process aftera track is written, and does not add a Table of Contents (contrastwith DAO). This allows the user to add another track later on, buttill the last track is added and the Table of Contents written, thecontents already on the media cannot be accessed. TAO is not to beconfused with multisession writing.

2.2.32 TracksEvery optical media or disk consists of a single spiral path, startingfrom the inner side and moving out, in which data is stored. Thisis called a track. A track is also used to denote the data portion ina session.

2.2.33 UDFUniversal Data Format is a file system used by optical media. Itoffers significant improvements over the older ISO 9660 used inCDs. UDF is the default format used in DVDs.

2.2.34 Video dataThe search for faster and more capacious optical storage media isfuelled by the need to distribute video of better quality. This wasevident in the emergence of DVD and now in the development ofBD and HD-DVD. High Definition (HD) video refers to a videostream that meets or exceeds the resolution of 1280 x 720 pixels.In contrast, DVD Video supports resolutions up to 720 X 576 pixels,and Video CD supports a maximum of 352 x 288 pixels. Non-HDvideo is also referred to as Standard Definition (SD) video.

MPEG1 is the compression format used in VCDs, while MPEG2is used in DVDs. The next generation media support multiple com-

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pression formats like H.264 (an MPEG4 format) and VC1 (based onWindows Media Video 9), besides MPEG 2. Protection of the videocontent is also another factor influencing the adoption of neweroptical media. Next-generation discs use Advanced Access ContentSystem (AACS) and High Definition Content Protection (HDCP) toprevent unauthorised use.

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2.3 Flash Drives

2.3.1 Bootable Flash DriveModern motherboard BIOSes allow USB Flash Drives to be used toboot the system.

2.3.2 Compact FlashCF cards are based around NANDFlash technology, though initially itused NOR Flash technology. It wasdeveloped by Intel, and is the oldestformat of Flash memory. The theo-retical maximum capacity of CF is137 Gigabytes. The transfer speedshave improved with every version ofCF, with the latest version 4 CF cardscapable of data transfers of 133Megabytes per second.

2.3.3 Flash Memory“Flash” Memory loosely refers to any non-volatile, rewriteable, ran-dom access memory. A Flash Drive or Thumb Drive consists of aFlash Memory chip that stores the data, a controller that managesthe read/write operations, and a USB interface. Besides as an inte-grated unit, Flash memory also exists as distinct memory cardsthat can be plugged into Memory Card readers that have a USBinterface. Memory card types include Compact Flash, SecureDigital, Multimedia, xD,Memory Stick, and more.These differ in their work-ing, but offer similar func-tionality.

2.3.4 Memory StickDeveloped by Sony, it isavailable in different ver-sions, like Memory Stick

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A SanDisk CompactFlash card

The Memory Stick Pro Duo is a faster andsmaller version of the Memory Stick

Pro, MS Duo, MS Pro Duo, and the latest, the Pro HG. The maxi-mum theoretical capacity is 32 GB, and the maximum transferspeed is 60 Megabytes per second.

2.3.5 MMCThe Multimedia Card was developed bySiemens and SanDisk. It relies on NAND Flashtechnology. Many types of MMC cards areavailable to suit different needs, like RS MMC(Reduced Size MMC) and Secure MMC. MMCcards have a theoretical maximum capacityof 128 GB, and the present maximum transferspeed is 40 Megabytes per second.

2.3.6 NAND / NOR FlashMost Flash Memory products are based on NAND Flash, and a fewuse NOR Flash technology. NAND and NOR refer to the logic gatesused to manage the contents stored in memory. NAND Flash typi-cally lasts for a much larger number of read/write cycles.

2.3.7 Secure DigitalThe SD card was developed by Toshiba, Panasonic, and SanDisk. Ituses NAND Flash, and is mostly used in smaller devices like mobilephones and cameras due to its smaller size as compared to CFcards. SD cards offer a maximum theoretical capacity of 128 GB,and a peak data transfer rate of 20 Megabytes per second. SD cardsare also available in smaller sizes, under the names of MiniSD andMicroSD. SD High Capacity (SDHC) is a newer version of SD that isnot backward-compatible, and offers capacities above 2 GB.

2.3.8 xD CardThe Extreme Digital Card was developed by Olympus andFujifilm—camera manufacturers—for use in their digital cameras.xD cards are comparatively slower, offering a maximum speed of 5Megabytes per second. They also have a theoretical maximumcapacity of just 8 GB.

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An MMC card

This chapter covers the peripherals—that is, componentstypically associated with a computer system but not reallyconsidered a part of “the computer”. This includes the key-

board, mouse, printer, scanner, UPS, and also the system’s powersupply unit (PSU).

Peripherals AndOther Components

III PERIPHERALS ANDOTHER COMPONENTS

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3.1 The Power Supply Unit

The role of the Power Supply Unit (PSU) is easily overlooked—sinceit comes bundled with the cabinet—and rarely gets special men-tion. With more and more power-hungry components beingplugged into PCs, the need for a proper PSU becomes important.

3.1.1 AmperageThis refers to the value of the current carried by a power cable, andis expressed in Amperes. Each of the voltage “rails” has an associ-ated amperage. Since 12 V is used to drive all the motors (harddisk, optical drives), and also power the graphics card(s) (in thecase of additional power being needed), it is recommended to buya power supply unit with higher amperage in the 12 V rail.

3.1.2 ATX Power Supply UnitPSUs are available in different form factors, with the ATX form fac-tor being the most widely-used. The ATX power supply is notdirectly controlled by the user; the motherboard controls it. ATXspecifications have been updated from the original so as to sup-port additional, power-hungry components. The latest version is2.2—it includes specifications for the 24-pin motherboard powerconnector (the original specifications included only a 20-pinpower connector), the 12 V 4-pin motherboard power connector,and the 6-pin PCIE graphics card power connector.

3.1.4 EfficiencyEnergy is lost during the conversion from AC to DC—mostly in theform of heat. The greater the amount of DC generated given a cer-tain AC input, the better the efficiency of the unit. The quality ofcomponents used in the PSU influences its efficiency.

3.1.5 Modular Power SupplyThese are power supplies that allow users to connect required cablesonly when needed, thus avoiding the clutter seen in most power sup-plies. These only have sockets for the required connections, thoughsome have the motherboard connector preinstalled.

3.1.6 RailsA PSU generates different volt-ages. All cables carrying thesame voltage constitute a rail.In a PSU, the cables are colour-coded: the Red cable carries +5V, the Yellow cable carries +12V, the black cable is Ground,and so on.

3.1.8 SMPSSwitching-Mode (or Switched-Mode) Power Supply refers to thatclass of devices that use a switching transistor (along with othercomponents) to convert AC current into DC current of differentvoltages. The switching transistor is used since the mode of opera-tion—constantly switching off and on, effectively “chopping up”the input power—is the most power-efficient. Using the samemechanism as in adapters for single devices would result in sig-nificant loss of energy as heat during the conversion process.

3.1.9 Standby PowerIn ATX power supplies, the user cannot directly power up theSMPS. The SMPS is connected to the motherboard, which con-trols it. Standby power is the minimal power (at 5 volts) that isused to keep the motherboard active even when shut down bythe user. This allows the system to be powered up manually bythe user by depressing the power button on the cabinet (whichactually passes a signal to the motherboard, not to the powersupply), or automatically by power-up events like sending a sig-nal over the network (Wake on LAN) or by setting a wake-up timein the motherboard BIOS.

3.1.10 WattageThis refers to the maximum power in watts that the PSU can pro-vide. This is a peak value; the effective power will be less than this.A PSU that provides at least 20 per cent more power than what isneeded by the system is recommended.

IIIPERIPHERALS ANDOTHER COMPONENTS

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A modular power supply avoids wireclutter

3.1.11 Power ConnectionsA few plug types seen in modern power units are:

m 20 / 24-pin Motherboard Power ConnectorThe 24-pin power connector adds four additional pins to theoriginal 20-pin specification. Many SMPSes offer a 24-pin plugwith a detachable 4-pin section that can be used to plug in toolder 20-pin sockets. The fouradditional pins provide addi-tional power to the mother-board, and some motherboardswith the 24-pin socket will notboot with the 20-pin plug.

m 4-pin 12 V ConnectorLike the 24-pin plug, the 4-pin12 V plug is needed to provideadditional power to the moth-erboard. Booting will not bepossible if this additionalpower is not provided to themotherboard.

m 4-Pin Molex ConnectorUsed to power hard disks, opticaldrives, cabinet fans, etc. Sometimesthis may also be used to provide addi-tional power to the graphics card, if ithas the socket.

m 4-Pin Floppy Drive ConnectorFor the floppy drive, of course, if it’spresent.

m 6-pin PCIE ConnectorPowerful graphics cards require morepower than the 75 watts that can be


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A 24-pin motherboard powerconnector with four detatchable pins

A 12 V 4-pin connector

A 4-pin molex connector

provided by the PCIE bus, so there are addi-tional power sockets on the card. Power sup-plies with the 6-pin connector are labelledSLI / CrossFire Ready.

m SATA power connectorSATA drives require a different 15-pin powerconnector. Most motherboards bundle a 4-pin Molex-to 15-pin SATA converter.

3.1.12 SMPS FanThe fan is used to cool the components inthe SMPS. Since it sucks air out of the cab-inet, it also helps reduce the temperatureof the system.

3.1.13 Y-SplitterThis is used to increase the number of freepower connectors. The Y-splitter consists oftwo pins on one end and a socket on theother. The socket is used to connect to anyMolex converter. This is usually seen associ-ated with additional cabinet fans.


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A 4 pin floppy driveconnector

A 6 pin PCI-E powerconnector

A SATA power connector

A Y-splitter to powermore devices

3.2 Printers

Here are some terms common to both laser and inkjet printers.

3.2.1 Bidirectional PrintingIn older printers, data could be only be sent from the PC to theprinter. This meant no information about the status of the printjob could be transmitted to the user. Bidirectional printing allowedthe printer to convey messages to the PC, which made it easier forthe user to track print progress, and be informed about the statusof various parameters of the printer—ink level, for example.

3.2.2 Borderless PrintingThis feature is commonly seen in printers that also offer photoprinting. Normally, all printers restrict the user from printing theentire width and length of a paper, leaving a small border. But thiscan be manually overridden. Borderless printing is a feature thatallows the creation of photos that look similar to those availablefrom professional labs. When this setting is selected, the printerprints the entire width and length of the paper.

3.2.3 CMYKThis is the colour scheme used in printing technology. The nameis derived from the four constituents of the scheme—Cyan,Magenta, Yellow, and Black. Colour inkjet printers have reservoirsfor each of the colours. Some photo printers also carry additionalcolours like red, green, light cyan and light magenta to offer bet-ter colour fidelity.

3.2.4 Draft Mode / Ink Saving mode / Toner Saving ModeThese refer to an alternative mode of printing where the printeruses less ink or toner to print. This is also the fastest mode of print-ing, and is ideal for trial prints.

3.2.4 Duplex PrintingRefers to the ability to print on both sides of a page. This is man-aged by the printer by ordering the pages in the print queue so


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that only alternate pages are printed first. After the first printcycle, the pages are inverted and printed on the reverse. In auto-matic duplex printing, the printer manages all the steps withoutrequiring user intervention. In manual duplex printing, after thefirst print cycle, the user must reinsert the pages in the paper tray.

3.2.5 Duty CycleA printer’s construction is capable of withstanding only a certainworkload, expressed in the number of pages that can be printed ina unit of time. The Monthly Duty Cycle is the workload that aprinter is designed to handle in a month, and is expressed interms of pages per month.

3.2.6 Network Printers / Workgroup PrintersSuch printers have a LAN port and can be plugged into a hub orswitch and used by any PC on the network. Since it is not connectedto any particular system, a PC is not needed to control the printer.

3.2.7 Printer BufferEvery printer has some memory on board, called the buffer,where content that needs to be printed is stored if the printer iscurrently printing. If the buffer is full, the printer will use the sys-tem RAM. Some printers come with upgradeable memoryoptions. Using the printer buffer relieves the PC’s resources.

3.2.8 Paper Capacity / Tray CapacityThe number of pages that can be stored in the printer tray. Mostprinters come with at least a 100-page tray capacity.

3.2.9 Paper JamA paper jam refers to when a sheet of paper gets stuck in the print-er. This can happen due to many factors, like page curl, page mois-ture, the roller not being clean, etc.

3.2.10 Paper PathThis refers to the route the paper travels in the printer during theprinting process. Complicated paper paths make it difficult to


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print of thicker media, besides increasing the chances of paperjams. Some printers print on the reverse side of the page, with ref-erence to how the paper is placed in the tray, indicating a U-shaped paper path.

3.2.11 PictBridgeA protocol that allows digital cameras and photo printers todirectly interact without the need to connect through a PC.

3.2.12 PostScriptA device-independent printing language. Documents sent forprinting from any system are first converted into Postscript.

3.2.13 PPMThis refers to the maximum pages that can be printed by the print-er in a unit time, expressed as pages per minute (ppm). Printingspeed varies with the content, coverage, and colour qualities.Printing pictures takes more time than text, printing closely-typedtext takes more time than printing double spaced text, and print-ing a colour image takes more time than printing the same imagein monochrome.

3.2.14 Print JobThe pages sent to the printer at one time together constitute a job.

3.2.15 Print MediaThe surface on which a printout is taken. Most printers allowprinting on normal paper sheets as well as thicker envelope cov-ers. Photo printing requires the much thicker photo paper whichis specially treated to prevent ink blot. The paper path influencesthe print media that is supported by the printer.

3.2.16 Print QualityPrinters support printing at different quality settings, usuallytermed Draft, Normal, and Best. The quality setting influences theprint speed. In draft mode, the print resolution is lower, as is theamount of ink or toner used. Best mode gives the highest possible


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resolution, with a normal amount of ink, as in Normal mode. Thetime required for printing increases along with the resolution.

3.2.17 Print QueueDocuments can be sent to a printer even while it is already print-ing a document. These documents are stored in the print queue.Depending on the size of the printer buffer, the print queue canbe on the printer or in the system. If the queue is in the printer,disconnecting the PC after a document has been sent to the queuewill not cause the queued documents to be lost.

3.2.18 ResolutionThis refers to the number of dots per square inch that a printercan print. The greater the resolution, the better the smoothnessand clarity of the printed matter. Most current inkjet printersoffer resolutions of up to 1200 x 1200 dpi, while the photo print-ers go up to 4800 x 4800 dpi. Laser printers usually offer 600 x 600dpi with the better ones touching 1200 x 1200 dpi.

3.2.19 Toner / Cartridge capacityThe number of pages that can be printed on a singlecartridge/toner. This figure is subjective and differs with test con-ditions. Usually, text printing capacity figures are based on a “5per cent coverage”, meaning the printed matter only covers 5 percent of the total paper surface.

3.2.20 Toner / Cartridge RefillingBudget laser printers and all inkjet printers have ink reservoirsthat need to be discarded once the ink is depleted, as recom-mended by the manufacturers. Refilling usually involves usingcrude methods (undertaken by the user) to replenish the ink /toner levels, and can be achieved at a fraction of the cost of buyinga new cartridge. But doing so usually voids the manufacturer war-ranty, and can result in reduced print quality.


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3.3 Laser Printers

3.3.1 FuserAfter the pattern on thedrum has been passed onto the paper by rolling, itpasses through the fuser,where heat is applied tofuse the pigment particlesto the paper.

3.3.2 Multicolour PrintersThese printers have tonersfor each of the coloursCyan, Magenta, Yellow, andBlack. In most printers, the paper passes through all the four ton-ers in sequence, accepting each colour component to complete theprint image.

3.3.3 Printer DrumIn laser printers, the drum is used to transfer the file imageonto paper. The surface of the drum is charged selectively by alaser, based on the pattern to be printed. When brought in con-tact with the Toner, the charged areas attract the toner particlesto complete the pattern on the drum. When the paper is rolledover the drum, the pattern is transferred on to it. In many entrylevel models, the Drum and Fuser are combined with the tonerhopper, so when the toner is depleted all the components haveto be discarded.

3.3.4 TonerThis refers to the fine electrostatically charged powder that is usedas the medium in a laser printer. It consists of minute particles ofpigment and plastic. Monochrome printers have just a black toner.Multi colour printers have toners for each of the colours Cyan,Magenta and Yellow (besides black). The toner is packed into areceptacle called the Toner Hopper.


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A colour laser printer

3.4 Inkjet Printers

3.4.1 Bubble Jet / Thermal Inkjet PrinterThis is a type of Inkjetprinter that uses heatto cause ink droplets tobe sprayed on to thepaper. This is the mostwidely used technologyin Inkjet printers. Thedroplet size in the lat-est printers is adver-tised as 2 picolitre. (1 litre = 1,000,000,000,000 picolitres).

3.4.2 CartridgeIn inkjet printers, the colour is stored in reservoirs called car-tridges. Cartridges can be individual where a single cartridge car-ries just one colour of ink or Combined, where each cartridge car-ries more than one ink within. Needless to say, if one of thecolours in the combined cartridge is depleted, the entire cartridgeneeds to be discarded.

3.4.3 Photo PrintersWhile many normalinkjet printers can alsoprint photos, PhotoPrinters are printersspecially created toprint photos. Presentlyall of these are inkjetprinters. They are of asmaller size and usespecial photo paper inthe usual photo sizeslike 4 X 6 etc. Theyallow printing withoutconnecting through the


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A typical inkjet printer

A portable photo printer

PC by using PictBridge. They also have interfaces to connect digitalcamera or memory cards, and a screen to preview the photo. Somealso allows rudimentary editing of the photo before printing.

3.4.4 Print HeadIn inkjet printers, the cartridges and associated circuitry areloaded on a block that is moved along the width of the page dur-ing the printing process. This is called the print head. Some man-ufacturers like HP fuse the print head and the cartridge into a sin-gle unit which needs to be discarded once the cartridge is deplet-ed. Others like Canon, separate the print head from the cartridge,allowing just the cartridge to be replaced when it is depleted.


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3.5 Scanners

3.5.1 ADCAnalogue-to-Digital Converter refers to the device employed toconvert analogue signals into digital form. In a scanner the volt-ages (analogue) from the CCD are passed to the ADC to be con-verted into binary (digital format).

3.5.2 ADFAutomatic document Feeder is an attachment seen in somescanners that can load the pages that need to be scanned, auto-matically into the scanner. This allows scanning without anymanual intervention.

3.5.3 Bit DepthThe amount of bits dedicated to capturing information from thescan subject. For greater detail, more bits need to be captured. A24 bit depth allocates 8 bits or 1 byte per colour in RGB.

3.5.4 CCDCharge Coupled Device refers to the optical sensor used to detectthe intensity in the reflected light. These devices are capable of con-verting the light into electric energy with corresponding intensity.Higher intensity of light generates higher voltage electric impulse.For colour scanning the CCDs are coated with either of the coloursRed, Green, Blue to register the colour under each filter.

3.5.5 Document ScannersThese are special type of Scanners that aredesigned for scanning large number ofdocuments. Here rather than have a mov-ing scan head, the scan head is fixed andthe paper is fed underneath it.

3.5.6 Flatbed ScannersThese scanners have a sheet of glass overwhich the object to be scanned is placed. The scan head consisting


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A document scanner

of the light source, the reflecting mirrorand the CCD array is moved under theglass sheet to scan the subject.

3.5.7 Hand Held ScannerThese are smaller scanners that rely on theuser’s movement to scan the documentbelow it. These can be in the formof Bar Code Scanners which areused to record bar codes on pack-ages or as Pen scanners wheremoving the scanner over the doc-ument captures it’s contents.

3.5.8 Interpolated ResolutionIf the hardware is unable to pro-duce the resolution, the softwarecan interpolate the values of two points to arrive at the values of apoint in between them. This would be the interpolated resolution.Scanners achieve a higher resolution by Interpolation.

3.5.9 Negative ScannersThese scanners are used to scan photographic film negatives. Inthese scanners the optical sensor and the light source are on oppo-site sides of the scan subject. The scan result is the developed photo.

3.5.10 OCROptical Character Recognition refers to the process of identifyingtextual data present in an image file. All scanners come with abundled OCR software. Good OCR software can identify textualand graphical data and retain the formatting of the original doc-ument. For best results, OCR software need a scanning resolutionhigher than 200 dpi.

3.5.11 Optical ResolutionIf the resolution can be achieved by the hardware, it is the opticalresolution. Optical resolution is the product of the number of


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A Flat bed scanner

A pen-shapedhand-heldscanner

A Bar codescanner

CCDs accommodated in one inch of a row on the sensor and thenumber of times the CCD captures light as the scan head rolls adistance of 1 inch over the subject.

3.5.12 ResolutionThis refers to the number of distinct points in a square inch thatcan be detected by the scanner. Resolution can be of two types :optical and interpolated.

3.5.13 RGBThis refers to the scheme which uses Red, Green and Blue (RGB) asthe primary colours. The other colours can be expressed as a com-bination of these colours in varying intensity.

3.5.14 Scan SpeedThis is expressed as the time it takes the scanner to scan an object.This varies with the mode (colour, grey scale) and scan resolution.

3.5.15 TWAINA term frequently used with regard to image capturing deviceslike Scanners and Webcams, TWAIN is the image capture API thatis needed to communicate with image capture devices. It is usual-ly bundled with the device drivers.

3.5.16 Multi-function DevicesMFDs or Multi-function Devices combine the functionality of aPrinter and Scanner. Thisallows them to be used also asa copier. Some MFDs also addadditional facilities like a dialup modem that can be used tofax images scanned with thescanner. MFDs are also calledAll in Ones.


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MFDs usually look like small photocopiers

3.6 Mice

3.6.1 CPI / DPIShort for Counts per Inch / Dots Per Inch, this is the number ofunique points that can be detected by the sensor in one squareinch area. The greater this value, the greater the capability of themouse to detect movements (sensitivity).

3.6.2 Laser MouseThis is the latest innovation in pointing technology. Moving a stepahead of the optical mouse, which uses normal light, the Lasermouse uses an infrared Laser beam (from a Laser Emitting Diode)to illuminate the surface. A laser sensitive sensor is then used totrack changes in the surface. Due to the focussed nature of thelaser beam, the Laser mouse can achieve 20 times the sensitivity ofthe optical mouse, besides being able to detect differences on sur-faces that befuddle an optical mouse.

3.6.3 Mechanical MouseThis mouse uses a ball to rotate two slit disks placed in the X and Yaxis. The slit disks are placed between a set of light source and opti-cal sensor. Any rotation of the disk causes a the slits to cut the beamof light received by the sensor which is translated into changes inthe respective axis. Any movement of the ball is thus translated intochanges in the X and Y axis. Mechanical mice are on the way out dueto the advantages offered by the equally priced optical mice.

3.6.4 Mouse DriverUsually the default driver offers the basic functionality of a 2 buttonscroll wheel mouse. To use the features of the mouse optimally, thedriver created specifically for the mouse needs to be installed. Themouse driver allows the buttons on the mouse to be reconfigured.

3.6.5 Optical MouseThe Optical mouse employs a camera or optical sensor to con-stantly take images of the surface beneath the mouse. Any changesin the surface is detected and the differences in the x and y posi-


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tions compared to the previously recorded image is transmitted tothe OS. A dedicated light emitting diode (LED) is used to illumi-nate the surface to make detection easier. Since the camera scansthe surface for changes, it’s task is made difficult if the surface isdevoid of any distinguishing pattern or is highly reflective.

3.6.6 Refresh RateRefresh rate is the number of images taken by the optical sensorof a mouse. This is variable and usually in the hundreds per sec-ond. A higher figure means a quicker response.

3.6.7 Scroll WheelThis is the wheel found in between the main two mouse buttons,and can be used to scroll through a document. This is the defaultbehaviour as set by the default driver. The mouse driver can beused to allocate a different function for the wheel.

3.6.8 TrackballThis is seen on some mice as afreely moving sphere that can beused to more accurately positionthe cursor on the screen.

3.6.9 Wireless MouseThis mouse does away with theneed for wires by using radio wavesto communicate with a base sta-tion that is connected by wires tothe system, usually to the USBport. The mouse has an independ-ent power source, usually in theform of batteries, or can berecharged by plugging into thebase station. Since radio waves canpass through objects, there is noneed to position the mouse infront of the base station to use it.


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A classic trackball mouse

Wireless mice give you a lot offreedom

3.7 Keyboards

Keyboards are the default input device of a system.

3.7.1 Ergonomic KeyboardThis keyboard is designedkeeping the natural posi-tion of the hands. Since thewrists are stressed when thepalms are positioned at anangle to the arm, the key-board was redesigned toplace the keys in the form ofan arc, with the key switches split down the middle, allowing theuser to keep the wrist unbent. Some keyboards also provide a wristrest for the wrists.

3.7.2 Gaming KeyboardThese are special keyboardsthat are built for gamers. Inmost games a limited set ofkeys are used, and the posi-tion of these keys are isdetermined keeping agamer’s needs in mind. Adedicated gaming keyboard offers a more user friendly layout ofkeys, and each key is programmable.

3.7.3 Multimedia / Internet KeyboardThese refer to keyboards that have additional keys that are config-ured to launch special programs or perform certain tasks likeincreasing or decreasing the volume of the media player orlaunching a browser.

3.7.4 QWERTY / DvorakTwo schemes for key placements on keyboards. The QWERTYscheme is more popular, and gets its name from the arrangement of


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The original ergonomic keyboard

The Logitech G15 for gamers

letters in the first row ofthe keyboard. The Dvorakscheme was introduced byAugust Dvorak, who arrivedat the placement based onhis observations about thefrequency of letter usageand human physiology.

3.7.5 RSI Repetitive Stress Injury refers to the condition caused by pro-longed use of the keyboard and mouse. This is characterised bypain in the wrist and fingers and is attributed to bad posture andinsufficient support while typing. Using ergonomic keyboards canreduce chances of RSI.

3.7.6 Typematic Rate / Repeat RateThis refers to the speed with which letters are repeated when thekey is pressed. A high repeat rate causes many letters to be input.

3.7.7 Wireless KeyboardThis keyboard uses radio wavesto carry the data to the system,thus avoiding the need forwires. The keyboard communi-cates with a base station thatis connected to the system,usually through the USB port.Since the keyboard needs addi-tional power to create the radio signals, it uses batteries. Wirelesskeyboards can also be based on Bluetooth technology and InfraRed technology, the latter requires that the keyboard and sensorbe in visible range.


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The Dvorak keyboard layout

A wireless keyboard

3.8 Webcams

Webcams are important com-munication accessories that areused in conjunction with chat-ting on the Net. A few termsassociated with webcams arediscussed next.

3.8.1 Actual ResolutionThis is the actual number of pix-els that the camera CCD cancapture. This is expressed in pix-els (or megapixels).

3.8.2 AVIAudio Video Interlace is a method for storing these two data streamsby interleaving them. AVI is a popular file format. Webcams can beused to record video data which is stored in AVI format.

3.8.3 CCDCharge Coupled Devices are optical sensors that are needed toconvert the optical data into electrical impulses. These can becoloured to capture data related to each colour in the RGBscheme (Red, Green, Blue).

3.8.4 CompressionUncompressed Video data is quite data intensive, and for transfer-ring this data over the net one would need very high speed inter-net connections. Compressing the video streams reduced the filesize, without causes any significant loss in quality. Different web-cams use different codecs to compress the video.

3.8.5 FPSFrames per second refers to the frequency with which the webcamupdates the CCD. A high refresh rate means that the capturedmotion is smoother. Most webcams capture at speeds of 25 fps.


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A webcam

3.8.6 Interpolated ResolutionThe colour of the points between two pixels can be estimated bysoftware. This is used to boost the resolution of the camera. Suchresolution is called interpolated resolution.

3.8.7 MegapixelA megapixel = 1,000,000 pixels. This refers to the resolution ofthe camera.

3.8.8 ResolutionThe number of pixels that can be captured by the CCD is it’s reso-lution. This is expressed as the number of pixels. Resolution can beactual or interpolated. The webcam can offer the maximum reso-lution for taking static photos while take videos at a lower resolu-tion. Resolution can be expressed in the number of pixels in thehorizontal and vertical axis, for example 640 X 480, or as a totalnumber of pixels on the CCD, for example 1.3 megapixel.

3.8.9 TWAINThe image capture API (application programming interface) that isneeded for an image capture device, like a Webcam to interactwith the system.

3.8.10 Video CaptureSimilar to audio recording, Video Capture is the term used todenote the process of recording video data by using analogdevices, like Webcams.

3.8.11 Video ConferencingA term used to denote a meeting of remotely located people overtelecommunication lines or the internet with utilising the servic-es of microphone and webcam. All the parties in the meeting needto have both a webcam and microphone to be seen and heard.

3.8.12 Video StreamingThis refers to the practice of sending video data over the networkto be viewed at the same time (and not be recorded).


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3.8.13 ZoomingThis refers to the magnification of the target either by using lenses(optical zoom) or by using software methods (digital zoom). Digitalzoom usually results in loss of clarity since the existing picture ismerely expanded causing the pixels to become apparent.

3.8.14 Tablet This is another device thatcan be used to record userinput. It is most suitable torecord user handwriting ordrawing. The Stylus is the penshaped device that is used towrite on the touch sensitivetablet surface to capture thepattern. The stylus can haveone or more buttons on it.

3.10 Gaming Accessories

These are used specifically forenhancing the user’s experiencewhile playing games. Theseinclude driving wheels, gamepadsand joysticks / flight sticks.

3.10.1 2-Axis / 3-Axis GamepadThis refers to the number of axeswhich can be effected by buttonson the gamepad. Usually the threeaxis functionality is best utilisedin case of Flight simulation games.

3.10.2 Force FeedbackThis is a system of communication between the system and thegaming device. Using force feedback it is possible for the game


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Tablets can even replace mice

A typical gamepad

software to send back special signals that effect the way the gam-ing device handles, like vibration. Every Force Feedback compati-ble gamepad has a few type of vibration sequences stored in it. Thesoftware only passes a signal to the gamepad to execute one ofthese vibration sequences. Force Feedback is also used to createrealism in driving wheels wherein the rotating resistance of thewheel is increased or decreased based on various factors present inthe game.

3.10.3 HIDHuman Interface Device are a class ofdevices that usually plug into the USBport and enhance user interaction withthe system. HID also includes gamepadsand joysticks and also USB mice and key-boards.

3.10.4 VibrationSome joysticks contain motors thatrotate when provided signals. Theserotating motors impart a sensation ofvibration. This effect is a part of theForce Feedback technology.


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A flight stick with forcefeedback

3.11 UPS

Uninterruptible Power Supplies are aclass of power backup devices thatmeet the strict power requirements ofPCs. PCs can tolerate a power outagewithout loss of data if power isrestored within 10 milliseconds. Ifpower is not restored within this time,the PC malfunctions causing a loss ofdata. A power backup system thatmeets this criteria can be called a UPS.

3.11.1 AHShort for Ampere Hour, this is an indication of the capacity of thebattery of the UPS, and refers to the current that the battery cansupply (in Amperes) in an hour. The higher the AH value, thelonger the battery can power the system. The AH value should begoverned by the expected backup period, and not the load offeredby the system. There is little relation between the VA value of theUPS and the AH value of its battery. So a 600 VA UPS need not sup-port a system longer than a 500 VA UPS if both of them use a 7.2AHbattery for backup.

3.11.2 BatteryThis refers to the secondary battery, usually sealed Lead Acid bat-tery, used to store the charge to be used in the absence of utilitypower. Most 500 and 600 VA UPSs have a 7.2 AH battery inside.UPSes with external batteries also exist that allow additional bat-teries to be added to increase backup time. Larger UPSes use LeadAcid batteries as used by heavy vehicles for backup.

3.11.3 Line Interactive UPSThis type of UPS constantly checks the quality of the mains power.In case of any anomaly, like a reduction in voltage the UPS startsutilising the battery power and boosts the voltage going to the sys-tem. This system offers better protection than Offline UPS.


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A UPS with an internal battery

3.11.4 Offline UPSThis UPS powers the system through the mains power till it fails,when it switches over to the battery backup. This is the cheapestand most widely available UPS.

3.11.5 Online UPS / Continuous UPSThis is the most reliable of UPS since the system is never poweredby the mains. This type of UPS is mostly seen for servers or othercritical equipment. The UPS is always working and the system isbeing powered off the backup batteries. This ensures that anyproblems with the mains supply is never felt by the system. In thisscenario, when the mains power fails, there is no switchover.

3.11.6 Power Management SoftwareMany UPS bundle additional software that can be used to shut-down the system when the power level falls below a threshold. Aserial cable connects the UPS to the system so that the necessarycommands can be passed.

3.11.7 Switch Over TimeThis is the time taken by the UPS to switch from utility power tobattery power in the event of failure of utility power.

3.11.8 VAShort for Volt Amperes, this refers to the load bearing capability ofthe UPS. The higher the VA rating, the greater the supported load.The supported load refers to the total power requirements of thePC. Since electrically Watts = VA, the total wattage of the compo-nents of the system is a good indicator of the suggested VA ratingof the UPS that will be needed. It is recommended to leave someheadroom and settle for an UPS marked at least 20% higher.


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This is the chapter on multimedia, covering most of theterms you’ll come across related to displays, graphics andsound cards, and speakers. We’ve also included a brief sec-

tion on connectors.

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4.1 Monitors And TVs

The technologies driving monitors and televisions are similar.With the increasing use of PCs as media centres for entertainmentpurpose, the PC monitor is being replaced with larger displaysthat were once reserved for entertainment use.

4.1.1 Active Matrix LCD / TFT LCDIn such displays, each liquid crystal in the Liquid Crystal Display isconnected to a Thin Film Transistor (TFT) that powers it. Thisallows the liquid crystals in the matrix to be addressed muchfaster, allowing for faster response times (this is in contrast to aPassive Matrix LCD).

4.1.2 Aperture GrilleThis is an innovation in CRT technology that was developed bySony for their Trinitron series of TVs. Rather than dots of differ-ently-coloured phosphors, thin horizontal lines of the phosphorsare used. A layer of thin metal strips is placed over the lines. Thesemetal strips form the Aperture Grille. The electron beam isallowed by the grille to hit only the correct line of phosphor.

4.1.3 Aspect RatioThe ratio between the width and height of a display screen.Displays that offer an Aspect Ratio of 4:3 are called “regular” or“standard” displays. Displays that offer an Aspect Ratio of 16:9 or16:10 are referred to as widescreendisplays.

4.1.4 Component VideoThis form of video signal transmitsthe data to reproduce a colour imagethrough three channels : theLuminance channel, which containsinformation about the image’sbrightness / darkness or white / black(called the Y component), the blue

Component video cables

colour difference signal (called the Pb/Cb component), and the redcolour difference signal (called Pr/Cr). The value of the green sig-nal can be calculated from the values of the blue and red signals,to reproduce the original image. Component video cables usuallyhave three RCA plugs for each of the channels, as seen on DVDplayers. Component video offers better quality output than S-videoand Composite video.

4.1.5 Composite VideoFor regular TV broadcast-ing purposes, the videoinformation in the threechannels in Componentvideo is fused into oneand compressed. This isthe Composite video sig-nal. The fusion of the luminance and colour information chan-nels cannot be accurately undone at the receiver’s end, so there isa loss in quality. The composite video signal can be carried over asingle cable. For TV broadcasts, the audio signals are also com-bined with the Composite video and transmitted through coaxialcables, the connectors for which are seen on all TVs. Compositevideo offers the lowest video quality compared to Componentvideo and S-video.

4.1.6 Contrast RatioThis refers to the difference in luminosity between the brightestand darkest modes of the display. If the contrast ratio is high, theon-screen images are clear even when ambient light is high.

4.1.7 CRTIn CRT displays, a beam of electrons is accelerated under highvoltage and made to collide on a phosphor-coated screen. The par-ticular phosphor elements that are hit by electrons are illumi-nated. In monochrome CRTs, each pixel is represented by a singlephosphor element, while in colour CRTs, each pixel has threephosphors, each one capable of emitting red, green, and blue

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Coaxial Cables

light. The electron beam constantly scans the screen, startingfrom the top left corner and ending at the bottom right corner,refreshing one row at a time.

Cathode Ray Tube technology is the predominant—thoughdated—technology, still powering most monitors. The high voltageneeded to power up the display and the space the monitors occu-py, in addition to the eye-strain caused by the flickering of thescanning electron beam, are the reasons for looking for alterna-tives. The ability to display at any resolution without loss of clari-ty puts them at an advantage over LCD screens.

4.1.8 Dead PixelsDead pixels refer to unresponsive elements in a digital display.Since they can no longer control the flow of light from the backpanel, these pixels get displayed as spots on the screen that do notchange their colour.

4.1.9 DLPDigital Light Processing is the technology that drives projectorsand rear projection TVs. This technology, a creation of TexasInstruments, uses tiltable microscopic mirrors (micromirrors) tomanage the intensity of light available at the screen. The lightfrom a source is directed onto a micromirror, whose tilt influ-ences the intensity of reflected light passing to the screen. Theposition of the mirror when no reflected light reaches the screenis considered the Off position, and the position when the reflect-ed light is available in full intensity is the On position. Eachmicromirror represents a pixel in the final image. The chip con-taining the micromirror is called the Digital Micromirror Device(DMD). Each mirror is switched On and Off many thousands oftimes per second, and depending on the intensity of light neededon the screen, the proportion of the On and Off positions is varied.To get a colour image, the light from the source is passed througha colour wheel containing filters for the three colours (Red, Green,and Blue). Due to the switching mechanism of this technology, thedisplay is subject to the flickering effect as seen in CRTs.

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4.1.10 Dot PitchThe closest distance between two pixels on a screen. The smallerthe dot pitch, the better the image quality. The definition can varyfrom product to product. Dot Pitch can mean the distance betweentwo pixels arranged horizontally or diagonally; and depending onthe way the pixels are arranged, these values may differ.

4.1.11 FlickerIn CRT displays, the phosphor element gradually loses its lumi-nosity. If the interval between refreshes is long enough, the fluc-tuating levels of luminosity is noticeable to the eye, and is referredto as flicker. Higher refresh rates ensure that the fluctuation inphosphor luminosity is not noticeable, and flickering is lessnoticeable.

4.1.12 GhostingThis phenomenon is seen in LCDs with a low response time. Whendealing with any scene that involves fast motion, pixels that arenot quickly updated retain their previous state for a brief momenteven as the adjoining pixels have been updated, causing the eye todetect a double image, or “ghost.” Typically, a response time ofbelow 16 milliseconds would mean no ghosting.

4.1.13 HDTVA “High Definition TV” refers to a TV set that can produce a pro-gressive display of resolutions above 1080 x 720 (widescreenaspect). The widescreen aspect is important, since HD transmis-sion signals do not support the normal aspect.

4.1.14 Interlaced / Non-interlaced / ProgressiveThese are methods used to refresh a screen. When only alternaterows of pixels on the screen are refreshed at a time, the display istermed Interlaced. This is usually used to reduce the data thatneeds to be transferred through the interface. Since this refreshoccurs many times per second, it is not easily evident to thehuman eye, except in scenes involving fast movement, where thismanifests as jagged lines. A non-interlaced display refreshes all the

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pixels at the same time.Non-interlaced displaysare also calledProgressive Displays.Normally, Interlaced dis-plays have twice therefresh rate of a non-interlaced display.Interlaced displays areusually marked with an“i”, and Non-interlaced orProgressive displays are marked “NI” or “P”. Besides monitors,media devices like DVD players and TVs are also similarly marked.

4.1.15 LCDLiquid Crystal Display technology uses an array of liquid crystalssandwiched between two sheets of polarised filters to control theamount of light generated by a cold cathode tube allowed to passthrough to the front of the screen. The polarising filters arearranged in different directions of polarity, so that the light com-ing through one filter will be completely blocked by the other, inthe absence of the layer of liquid crystals. The shape of the liquidcrystal influences the amount of light passing through the secondfilter. By varying the voltage applied to the liquid crystal, its shapecan be controlled. In colour LCDs, one pixel is made up of three liq-uid crystals, each coloured Red, Green, or Blue.

4.1.16 Native ResolutionThis refers to the actual number of pixels in an LCD. Unlike CRTs,an LCD can only offer maximum clarity if the incoming signal isof the same resolution as the native resolution.

4.1.17 Passive Matrix LCDThis is the older type of LCD, and is still used in smaller displays.Here, the liquid crystals making up the display are addressed bytheir row and column number, and each row and column has asingle controlling circuit. This form of addressing doesn’t allow

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An Interlaced Frame draws lines alternately

fast responses, and this is most noticeable in large screens, whereit manifests as the ghosting effect.

After Active Matrix LCDs were invented, this technology beganto be referred to as Passive Matrix.

4.1.18 Pixels“Pixel” is a contraction of PICture ELement, and it refers to thesmallest unit on a display medium that can be independentlymanipulated. In colour displays, a pixel is usually made up of sub-pixels / subelements for each of the colours Red, Green, and Blue.

4.1.19 Plasma TechnologyPlasma is ionised gas. Displays made using Plasma technology usethree sealed cells, each containing phosphor elements and plasma,to represent a pixel. The plasma sealed in the cells is usually derivedfrom the gases Xeon or Neon. The phosphor elements in each of thethree cells are either of the three colours Red, Green, and Blue. Whenan electric charge is passed through a cell, it excites the plasma,which causes the phosphor in that cell to light up. The combinationof the three colour cells make up the colour of the pixel. Like in anLCD, displays based on Plasma technology have a native resolution.

4.1.20 RGBRGB refers to the display scheme that identifies a colour based onthe strength of each of the constituent colours Red, Green, andBlue. In digital systems, each of these colours is allocated 8 bits,and so can have 256 possible values. The RGB system, therefore, isa 24-bit colour code with about 16 million possible colour combi-nations. Video recording devices capture data in RGB format, butsince transmitting in RGB format is bandwidth-intensive, the sig-nal is compressed (with loss of quality) to other formats likeComponent, Composite, or S-video.

4.1.21 Rear-projection TVSuch TVs employ a projector placed inside the TV to project thevideo image onto the screen in front. By increasing the distance

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between the screen and the projector, it is possible to increase thevideo size without significant additional expenditure. The projec-tor used can be of the CRT, LCD, or DLP type.

4.1.22 Refresh RateIn a CRT display, the refresh rate is the number of times per secondthat the electron beam scans through the screen. Since the beamtravels row-wise from the top to the bottom, CRT displays have tworefresh rates associated. The Horizontal Refresh Rate is the numberof rows scanned by the beam per second. This is usually in theorder of Kilohertz and is of not much importance. The VerticalRefresh Rate is the number of times all the rows in the screen arerefreshed, and this is in the range of 50 to 150 Hertz. Normal refer-ences to “refresh rate” are to the Vertical Refresh Rate.

4.1.23 ResolutionThe total number of pixels that make up a display is its resolution;it is normally denoted as the number of pixels on the horizontalaxis and on the vertical axis. A screen with 1024 x 768 resolutionhas 768 rows of pixels with each row having 1024 pixels.

4.1.24 Response timeIn LCDs, since the source of light is always on, the concept of refresh-ing is not applicable. Response time refers to the time it takes the liq-uid crystal to change shape. Since changing the shape also changesthe light passing to the screen, response time is defined in two alter-native ways. Black-to-black response time refers to the time it takesthe liquid crystal to switch from a shape that allows no light to pass(black) to a shape that allows all light to pass (white) and revert. Grey-to-grey response time refers to the time it takes the liquid crystal toswitch from any arbitrary shape to any other arbitrary shape, mak-ing a pixel change colour from one shade of grey to another. There isno common pair of shades of grey that is used by all manufacturers.Response time is usually mentioned in milliseconds.

Response time is an important factor that influences the dis-play’s performance when dealing with fast-moving images. If the

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response time is greater than 16 milliseconds, there will, typically,be blurring and ghosting effects visible.

4.1.25 S-videoThis form of video connection carries the display data over twochannels, the Luminance and Chrominance. The Luminance chan-nel carries the same information as the one in Component video,while the Chrominance channel contains the combined data ofthe Pb and Pr channels of Component video. This offers bettervideo quality than Composite video. S-video connections are pres-ent on graphics cards and DVD players, for example.

4.1.26 Shadow MaskThis refers to the fine mesh laid over the phosphor elements ona CRT screen. The mesh ensures that the electron beam onlystrikes the intended phosphor element. This enhances contrastin the image.

4.1.27 Viewing angleTwo types of viewing angles are referred to: Vertical AndHorizontal. These refer to the maximum angle from which thecontents on the screen can be viewed, with a contrast ratio of upto 10:1. CRT monitors offer the largest viewing angles—about 170degrees. In LCD screens, except for the latest ones, the most com-mon viewing angles are in the range of 120 degrees.

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4.2 Graphics Cards

“Graphics cards” refers to expansion cards that contain additionalhardware to ease the computational load on the CPU when deal-ing with graphics data. Graphics cards contains two importantcomponents, the GPU and the Frame Buffer.

4.2.1 AGPAccelerated Graphics Port is a type of expansion slot dedicated forthe use of graphics cards. The maximum bandwidth offered is2133 Megabytes per second.

4.2.2 Graphics ApertureSome part of the system RAM can be reserved for use by the graph-ics card to store data that exceeds its Frame Buffer. This is calledthe Graphics Aperture, or just Aperture. This value is set in the sys-tem BIOS.

4.2.3 Alpha BlendingThis refers to the process by which information in the alpha chan-nel is included with the colour characteristics of a pixel. The alphachannel carries information related to the transparence of thepixel, and is an 8-bit code capable of displaying 256 levels of trans-parence. A 32-bit colour scheme includes 8 bits of information forthe Red, Green, Blue, and Alpha channels.

4.2.4 Anisotropic Filtering (AF)The most advanced form of texture filtering (explained later), itworks in conjunction with bilinear and trilinear filtering to correctartefacts from a larger perspective. Since the user’s view revealsobject surfaces in different shapes—for example, a rectangular ceil-ing appears as a trapezoid—texture filtering has to ensure an eventransition of the texture laid on this shape, and not the originalshape of the object. Anisotropic Filtering ensures that bilinear andtrilinear filtering achieves the correct transition effects by chang-ing the sampling pattern based on the user’s perspective. AF canalso be denoted by the number of samples taken, like AF 8X.

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4.2.5 Anti-Aliasing (AA)Aliasing refers to the jagged edges seen onslanting lines in any rendered image. Anti-Aliasing is the process of removing or reducingthe effects of Aliasing. AA achieves smootherlines by taking a sample of the pixels aroundthe point and using this information to fill thejagged edges. The process can take differentforms, like FSAA or Full Screen Anti Aliasing,where all the pixels on the screen are sampledbefore making remedial modifications to theimage. FSAA can also offer better result if moresamples were taken. Depending on the numberof samples taken, AA is denoted as 2X (2 sam-ples), 4X, 8X, and 16X. Needless to say, takingthese samples requires processing power, and usually the highersample rates are achieved only by powerful graphics cards.

4.2.6 ArtefactsArtefacts are the defects that appear in a display. They are usually theresult of bottlenecks in the system rather than defects in the displayunit. Jagged edges and pixelated images are examples of artefacts.

4.2.7 Bilinear FilteringTo smoothen the texture at a particular point, a sample of values ofthe texels around the point is taken. This process is called BilinearFiltering, and is used to arrive at values within one mipmap.

4.2.8 Bump MappingA bump map is a set of values that contain information about theelevation of points on an object’s surface. After a texture has beenmapped, to increase realism, its surface can be modified accordingto the values in the bump map. This process is called bump mapping.

4.2.9 Core clockThis refers to the operating frequency of the GPU of the graphicscard. Like a CPU, the GPU, too, can be overclocked.

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An unantialiased frame

A 4x antialiased frame

4.2.10 DirectXA graphics programming API proprietary to Microsoft. Gamesbased on DirectX can only be played on a Microsoft OS. DirectX 10is the latest version of this API. To be able to experience softwarewritten in DirectX 10, one requires Microsoft’s latest OS (WindowsVista) and a DirectX 10 compatible graphics card.

4.2.11 Dual DisplayThis is a feature of graphics cards that can power two monitors atthe same time. In the case of analogue monitors, the graphics cardwill require two RAMDACs. In case of LCD monitors, two DVI portsare needed. The output image can be split across these monitors,creating one large image.

4.2.12 FPSA Frame is a static image created by rendering. To give an illusion ofmotion, many frames are constantly rendered. Frames per second(fps) is a measure of the rendering speed. A higher frames-per-secondrate of rendering ensures (an illusion of) smoother movement. Thisis also a measure of the computational abilities of a graphics card.

4.2.13 Frame BufferA buffer is a temporary storage area. The Frame Buffer refers to theRAM on the graphics card that is used to store the frames thathave already been rendered by the GPU.

4.2.14 GPGPUGeneral Purpose GPUs refer to those GPUs that can also be used toperform non-graphics work. GPUs have increased in computationalprowess to such an extent that they are capable of overtaking mostCPUs in their ability to manage numerical— specifically decimal—data, which forms the bulk of graphics data that they are speciallydesigned for. The GPGPU concept seeks to utilise this power of theGPU to perform general tasks that are heavy on number crunching,like weather simulations and space data manipulation. The factthat newer cards are increasingly programmable, allowing thedeveloper to use them for custom purposes, helps the cause.

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4.2.15 GPUThe Graphical Processing Unit is the computing core of a graphicscard. These chips are designed to perform computations on graph-ical data much more efficiently than can CPUs. Modern GPUs aremore complex than CPUs, if transistor count be considered. One ofthe fastest GPUs today, the GeForce 8800 GTX, has 754 milliontransistors, while the fastest CPU, the quad-core Intel Core 2 Quad,has 820 million transistors (including the 24 MB of L2 cache mem-ory). GPUs can be subdivided into different areas specialising in aparticular operation. The major sub-units are the StreamProcessors, TMU, and ROP. Newer GPUs are released quicker thanCPUs. The major manufacturers of GPUs are NVIDIA (the makers ofthe GeForce series) and ATI (the makers of the Radeon series).

Here are the features of a few GPUs:

4.2.16 Graphics MemoryMemory types used as system RAM can also be used for graphicscards in most cases. But high-end cards require memory fasterthan system RAM. GDDR2 was the first such special-purpose RAMused for graphics cards. The technology behind GDDR2 was differ-ent from that which powered DDR2, which was later introduced as

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GPUs ComparedGGPPUU

GeForce8800 GT

GeForce8600 GTS

RadeonHD 2600 PRO

Radeon3850

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system RAM. GDDR3, a creation of ATI, seen in many presentgraphics cards, uses a technology distinct from that of DDR3,which is used in high-end computers. The latest graphics cardsusing GDDR4 also have a presence in the market.

4.2.17 HDRHigh Dynamic Range is a relatively new display concept, only imple-mented in the latest GPUs. It refers to the range of lighting in whichthe detail of an image is preserved. Normally, visual elements thatare too dark or too bright, for example areas that are overshadowed,are not displayed with the same amount of detail as well-lit areas.Doing so saves resources since in any case the detail in these areasare not noticeable to the eye. But in HDR mode, even these detailsbecome noticeable. Rendering in HDR requires higher computation-al power, which has become possible with the latest graphics cards.

4.2.18 Memory Bus WidthThe width of the pathway between the Graphics RAM and the coreis called the Memory Bus Width. The wider the pathway, the fasterthe data can be processed.

4.2.19 Memory ClockThis refers to the operating frequency of the graphics RAM on thegraphics card. Depending on the type of RAM used, the effectiveand actual frequencies vary. In case of DDR2 and GDDR3 RAM, theeffective speeds are twice the actual speeds, since the RAM out-puts data twice during every clock cycle.

4.2.20 MipmappingThis refers to the use of images of differing resolutions dependingon the perspective distance between the user and the object in agraphical scene. At close range, the image is used at high resolu-tion to reveal all detail, but as the distance increases, since detailis no longer important, a low-resolution version of the image isused. Doing so saves on resources and doesn’t affect the visualquality of the creation. A mipmap is a table that contains the dif-ferent versions of the various images used in the scene.

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4.2.21 PCIEPeripheral Component Interconnect Express is the latest expan-sion slot type suitable for graphics cards. The slot commonly usedfor graphics cards has 16 lanes, each carrying data at 250Megabytes per second in one direction.

4.2.22 PolygonsModern computer graphics define apolygon as the smallest unit of animage. Any point in 3D space is calleda vertex. A polygon is any shape thatcan be defined by its vertices. The sim-plest polygon is a triangle, defined bythree vertices.

4.2.23 RenderingThis refers to the process of convert-ing a model into an image. A model isa wire-frame representation of anobject, which can have other properties associated with it, like tex-ture and lighting information. While rendering, all this informa-tion is applied to the model to create the final picture, usuallycalled a frame.

4.2.24 RAMDACRandom Access Memory Digital to Analogue Converters are thechips the are responsible for converting the digital data that isgenerated from the GPU into analogue signals that can be outputon analogue monitors (like CRTs). Since LCD monitors are digitalin nature, RAMDACs are bypassed when signals are directed tothe DVI port on a graphics card.

4.2.25 ROPThe Raster Operations Unit is the component of a GPU thatlends the final touch to the data before it is output to thescreen. Operations like Anti-Aliasing are done by the ROP. Datato be sent to an LCD monitor is directed to the DVI outputs. If

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The polygon model of a face

the data is to be sent to a CRT monitor, the ROP sends the datato the RAMDAC.

4.2.26 SBASide Band Addressing refers to use of the additional channelsincorporated by the AGP bus. Besides the 32-bit bus, the AGP spec-ifications created an additional 8-bit address bus, called the SideBand, for transfer of data requests. Using this channel, the 32-bitbus could be freed, thus improving data transfers.

4.2.27 SLI / CrossFireScalable Link Interface is a mechanism that allows the performanceof two or more graphics cards plugged into PCI Express slots to becombined. It was created by graphics card manufacturer NVIDIA towork with NVIDIA graphics cards only. CrossFire is a similar tech-nology launched by ATI (later taken over by AMD) that works onlywith their graphics cards. For SLI / CrossFire to work, the graphicscards must be of the same type, and the motherboard should sup-port the technology, besides having two PCIE X16 slots. The graphicscards are connected via a special cable called a Bridge Connector(though CrossFire models connect through the PCIE bus or one ofthe cards should be aCrossFire edition card). InSLI mode, one of the cardsacts as a master, and theoutput is available onlythrough it. The graphicsload is distributed in twoways. In Split FrameRendering, the displayarea is divided into twohalves horizontally, witheach card responsible forone half; in AlternateFrame Rendering, eachcard renders every alter-nate frame.

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A CrossFire setup

4.2.28 Stream ProcessorsThese refer to the Arithmetic and Logical Units (ALU) of the GPUwhich act on the shading instructions. These are called StreamProcessors. In earlier GPUs (prior to the GeForce 8XXX series andthe ATI 2XXX series), stream processors existed separately asVertex Shaders and Pixel Shaders. Stream processors are com-pletely programmable and can be used for either of the shadingjobs. These can operate at a different clock speed from the othercomponents of the GPU.

4.2.29 TexelsA TEXture ELement is the smallest unit of a texture image. Thesize of the final texture and the number of texels that are neededto create it are influenced by texture-filtering procedures.

4.2.30 Texture FilteringA process to ensure a smooth transition between areas using thesame texture but with different resolutions. Its role is similar tothat of Anti-Aliasing to ensure smoother slanting lines. Oft-usedtexture filtering procedures include Bilinear, Trilinear, orAnisotropic Filtering.

4.2.31 Texture MappingThis refers to the process of applying an image that represents thetexture / surface of an object to the model of the object. The modelusually consists of lines, and is called a wireframe.

4.2.32 TMUTexture Mapping Units are those components that are responsiblefor correctly orienting texture units to objects in the scene.

4.2.33 Trilinear FilteringWhen transitioning from one mipmap to another, the differencesin them can be obvious. Trilinear filtering works similar to bilin-ear filtering, except it takes samples from both mipmaps tosmoothen out the intervening edges.

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4.2.34 V-SyncVertical Synchronisation refers to the limiting of the graphics card’srendering rate to match the vertical refresh rate of the monitor.

4.2.35 VertexAny point in a 3D space is called a vertex, and can be defined by itscoordinates on the X, Y, and Z axes.

4.2.36 VIVOVideo In / Video Out refers to the ability of a graphics card acceptvarious video inputs like Component , Composite, or S-video, andalso send out its signals to external devices through these connec-tions. This feature is available in graphics cards that also providevideo capture functionality through additional hardware.Incoming video can be recorded by the graphics card and stored tothe hard disk, while the video-out function allows signals to be dis-played on larger screens like a TV set, which is preferable whenwatching videos. The GPU does not play a role in video capture.

4.2.37 Workstation Graphics CardsThis term refers to those cards that are specially tailored for use inWorkstations—computers used for pursuits like Computer AidedDesign and Video Editing. Internally, they are based on the samearchitecture as their Desktop counterparts. ATI and NVIDIA haveworkstation graphics cards under the brand names FireGL andQuadro respectively.

4.2.38 Z BufferIn a 3D scene, objects that are close to the viewer block objectsbehind them. From a computational point of view, both objectshave the same X and Y coordinates of the screen, but differ in theZ coordinate, which represents depth. A Z buffer is the storagearea where objects that have a greater Z axis value (and hence arenot in view) are stored. This makes it easier to reproduce themwhen a perspective change requires that object to be displayed.

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4.3 Speakers and Headphones

Briefly, speakers are devices that recreate a sound by convertingelectric signals into vibrations in the air with the use of an elasticdiaphragm. The vibrations are translated into sound by thehuman ear. The human ear is capable of distinguishing vibrationsranging from 20 Hz to 20000 Hz. (1 Hertz (Hz) denotes one vibra-tion per second).

4.3.1 ChannelsA sound source can be recorded with many devices, and thestream recorded by each device is called a channel. Single-channelsound is called Mono, whereas two-channel sound (one each forthe left and right sides) is called Stereo. Stereo playback creates asense of space and direction due to the differences in the playbackfrom each channel. A playback with five or more channels (4.1) iscalled multichannel.

4.3.3 Frequency ResponseThe range of frequencies that can be reproduced by the speaker isits frequency response. In actuality, no single speaker can coverthe entire audible range of the human ear.

4.3.4 Multiway SpeakersA multiway speaker contains more than one type of driver in thesame enclosure. Depending on the number of types of drivers in aspeaker, the speaker can be classified as 2-way (2 drivers in thesame enclosure), 3-way, etc. The different driver types—tweeter,midrange, woofer, full range—cover the entire audio spectrum.

4.3.5 PMPO Peak Music Power Output is the maximum output capacity of aspeaker. There is no standard procedure to calculate PMPO, andsince this value cannot be sustained by the speaker for morethan a brief period of time, it is not a reliable measure of thespeaker’s capabilities.

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4.3.6 RMSRoot Mean Square is theaverage power output ratingof a speaker, and is consid-ered a more accurate indica-tor of a speaker’s capabilitythan PMPO. The total RMS ofa system will be the sum ofthe RMS of all speakers inthe system.

4.3.7 AmplifierThis is the circuitry thatamplifies (increases) weakelectrical signals so that theycan be output through largerspeakers. Most headphonesdo not have amplifiers andrely on the amplifier of the sound card to generate the sound.Larger speakers have their own amplifiers since the sound carddoesn’t have adequate power.

4.3.8 SatellitesIn any multichannel speaker sys-tem, the small speakers that offerdirectional audio are called thesatellites. These are usually placedaround the listener.

4.3.9 SNRSignal to Noise Ratio is the differ-ence between the sound playedback and the accompanying noise created by equipment interfer-ence. It is an indicator of the quality of components used in thespeaker system, since higher-quality components tend to causeless interference. It is expressed in decibels, and the greater theSNR, the less the adulteration by noise.

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A 2-way speaker with tweeter and woofer

A 5.1 system with 5 satellites

4.3.10 Speaker systemsStereo speaker systems consist of two speakers, one for each soundchannel. A 2.1 system denotes two satellites and one woofer unit.Satellites can be added to the system to create a 4.1 system, con-sisting of two satellites each in the front and back. A 5.1 systemadds a centre speaker in the front to the 4.1 system. A 6.1 systemadds a central back satellite to the 5.1 system. A 7.1 system addstwo speakers at the same level as the listener to the 5.1 setup.

4.3.11 Speaker driverThe vibrating core of the speaker. This usually involves adiaphragm connected to a voice coil elastically suspended betweenmagnets. When electrical impulses are passed through the voicecoil, it is magnetised; the resulting interaction with the sur-rounding magnet causes the diaphragm to vibrate, which is inter-preted as sound.

4.3.12 TweetersSpeakers good at reproducing high-frequency sounds.

4.3.13 Woofer / SubwooferSpeakers that can reproduce low-frequency sounds well. In anyspeaker setup, the “.1” representsthe subwoofer.

4.3.14 Mid-range SpeakerSpeakers that are best at reproduc-ing frequencies in the 300 Hz to 5kHz range.

4.3.15 Full-range SpeakersSpeakers that can create sounds of almost all frequencies in theaudible spectrum. Most affordable stereo speakers that containjust one driver fall in this category. Audio quality is compromisedat both ends of the spectrum by such speakers.

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A speaker driver

4.3.16 TrebleThis refers to the higher audible frequencies in sound, typicallymusic.

4.3.17 BassThis refers to the lower audible frequencies in sound, typicallymusic.

4.3.18 Graphic EqualiserA device that can selectively fil-ter and modify various frequen-cies of a sound track. This canbe implemented in hardware,and you’ll have a set of pegs tobe pushed up or down tochange the intensity of therelated frequency. In software,you’ll have sliders in the mediaplayer. Depending on the num-ber of distinct frequency bandsit can filter, there are 2-band, 5-band, etc. graphic equalisers.

4.3.19 LFELow Frequency Effects refer tothe parts of the audio trackwith low frequencies, whichare directed to the subwoofer.The frequency is usually below120 Hz. The sound of a roll ofthunder, for example, is a LFE.

4.3.20 DolbyRefers to Dolby Laboratories, which conducts R&D on soundrecording and reproduction. It doesn’t have audio products of itsown; companies license Dolby technology to use it, along with thelabel, in their equipment. Dolby Digital uses a 5.1 speaker system

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A Hardware 10-band (stereo) graphicequaliser

20 band Graphic equaliser in Jetaudiomedia player

to create surround sound effects, and is commonly seen in con-sumer-grade speaker sets and sound cards. This technology is alsocalled AC3, and is used in DVD video to deliver surround sound.

4.3.21 THXLoosely speaking, this is a certification that the playback devicebearing the logo is of superior quality. The scheme was the brain-child of Star Wars creator George Lucas, who wanted his audienceto experience his movies exactly as he had created it. This led to theneed to ensure that every theatre in which his movie was screenedmet with stringent audio and video playback standards. So a THX-certified theatre offers the highest movie-viewing quality. This cer-tification was later extended to home theatre systems as well.

4.3.22 Intra-auralHeadphonesThese are in the form ofearplugs that are meant to beinserted into the ear canal.

4.4.23 CircumauralHeadphonesThe largest of the headphonetypes, these have large foam-padded ear cups that surroundthe ears. They are capable ofsignificantly damping ambientnoise. The spacious ear-cupscan also hold comparativelylarger speakers, or even multi-ple speakers, which offers thegreatest frequency response.

4.3.24 Supra-aural head-phonesThese headphones rest over the ear without enveloping them. Theytherefore allow ambient noise to interfere with sound reproduction.

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Intra-aural headphones

Circumaural headphones

4.3.25 EarphonesThese are small hemisphere-shaped headphones that can bepositioned right in front of theauditory canal. They some-times also have a retainingextension that goes around theear that prevents them fromfalling off.

4.3.26 Noise CancellationSound is in the form of vibra-tions. If two vibrations of the samemagnitude but inverse directions col-lide, they nullify. This is the ideabehind the concept of NoiseCancellation. Two type of NoiseCancellation techniques are used.Active Noise Cancellation uses micro-phones placed on the outside of theheadphones to detect ambient noise.This information is used to createsound waves opposite to the ambientsound, thus nullifying the ambient noise. An additional powersource is needed to drive the microphone, and this is usually inthe form a batteries fitted into each ear-cup. Passive Noise cancel-lation relies on blocking out ambient noise by ensuring a tighterfit between the ear and the speaker. This technique is better imple-mented in circumaural and intra-aural headphones.

4.3.27 ImpedanceThis is the load that a speaker puts on an amplifier. Speakers withlow impedance can be operated without external power, while speak-ers with higher impedances need external power to work. Higher-impedance speakers produce louder, and typically better, sound.

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Supra-aural headphones

Earphones

4.4 Sound Cards

Sound cards are expansion cards with chips to process audio infor-mation. With modern motherboards carrying such circuitryonboard, most users do not feel the need for a dedicated soundcard. Many onboard sound processors are capable of supportingeven 8-channel surround sound. Sound cards are used by audio-philes not satisfied by onboard sound quality, and professionalswho find the features offered by onboard sound limited.

4.4.1 ADC / DACThe Analogue-to-Digital Converter (ADC) is responsible for con-verting the analogue signals received through the sound sourceinto digital signals capable of being processed by the PC. Thereverse process of converting digital signals into analogue signalsto be passed on to the speakers is done by the Digital-to-AnalogueConverter. The quality of the conversion is influenced by theSampling rate and Bit rate.

4.4.2 Bit ResolutionThis refers to the amount of data that is used to store informa-tion about every sample while sampling (converting from oneformat to another). The better the bit resolution, the greater thefidelity of the recorded sound. Bit resolution is usuallyexpressed in bits.

4.4.3 Bit RateThe product of the sampling rate and the bit resolution is the bitrate. For example, if a conversion process takes 44.1 kHz as thesampling rate and 8 bits as the bit resolution per channel, the bitrate for the converted sound in mono would be 44.1 Kilobytes persecond, and stereo, 88.2 Kilobytes per second.

4.4.4 CodecA Codec, short for Compressor-Decompressor, is an algorithm usedto convert and play back audio in a specific format. Audio storedby a particular codec can only be played back if the codec exists on

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the system. Popular audio codecs include MP3 (MPEG Layer 3),AAC, and WMA (Windows Media Audio).

4.4.5 DecibelA measure of sound intensity, calculated as the logarithmic valueof a ratio of sound intensities. The basis is considered to be thethreshold of hearing for a normal human ear. Every other soundis expressed in decibels in relation to this base sound intensity. 0dB represents the threshold of hearing, while 120 is the higherlevel that the human ear can tolerate without feeling pain.

4.4.6 Dynamic RangeThis refers to the range of loudness of sounds that can be detect-ed by a recording device or reproduced by a speaker. This is meas-ured as the difference in the highest and lowest sound, in deci-bels. The human ear has a dynamic range of 120 dB. A highdynamic range of recording or playback is representative of high-quality equipment.

4.4.7 MIDIMusical Instrument Digital Interface is the default interface toconnect any digital musical instrument to a sound card. Thisallows data to be transferred across the sound card and thedevice, and allows recording of any composition to the system.Each MIDI port can connect to up to 16 compatible devicessimultaneously, enabling a single PC to control these devices.MIDI uses a standard set of codes that conveys informationabout how to produce the sound—rather than the sound itself—so MIDI files are small compared to the audio file for the samecontent. Since a MIDI file relies on the sound card’s wavetable tocreate an output, the results may vary with the sound card. The15 pin D-sub MIDI interface also doubles as a gameport to plugin compatible gamepads.

4.4.8 MonoAn audio stream that contains only a single data channel would becalled Mono (for monaural).

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4.4.9 Sampling RateThe conversion of analogue signals into digital format involves tak-ing samples of the sound track at regular intervals and convertingthis into digital data. The Sampling rate is the frequency of the sam-pling or the number of samples taken per second. The greater thesamples taken, the lesser the data lost in the conversion. CD Audiouses a 44.1 KHz sampling rate, that is, 44,100 samples per second.

4.4.10 StereoAn audio stream that contains two data channels of data, one eachfor the left and right perspective, would be called stereo.

4.4.11 Surround SoundThis refers to multichannel sound where there are at least four dis-crete sound channels, representing the front left, front right, backleft and back right channels. Surround sound can also comprise alarger number of channels.

4.4.12 Wavetable SynthesisA Wavetable refers to the set of sample sounds of different instru-ments stored on the sound card. The use of the Wavetable to cre-ate and store sounds is called Wavetable Synthesis. Since the con-tents of the Wavetable varies with sound card, the compositionneed not sound the same on all systems.

4.4.13 WAVWAV is a file format for uncompressed audio data.

4.4.14 Virtual SurroundNormal surround systems employ at least four speakers to create aspatial effect. Modern sound cards can create a similar effect withtwo speakers using advanced algorithms that can process the mul-tichannel audio source to identify the “spatialness” and create anapproximation by altering the stereo output. This is called VirtualSurround. While the totality of the “surroundness” can beachieved, the fidelity that is achieved with surround speakers can-not be duplicated. The reverse of the process is also seen, wherein

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a normal stereo sound source is processed and surround soundchannels suited for a 4.1 or higher speaker system is generated.

4.5 Interfaces

Here are some of the interfaces seen commonly on computers andTVs.

4.5.1 Analogue / mini D-Sub 15 /VGAThis is the standard interface for ana-logue monitors. It has 15 sockets.

4.5.2 AudioAudio connections are colour-codedwith Green for speaker output, Red forMicrophone input, and Blue for other lineinput.

4.5.3 CoaxialThis connector is usually seen in TV antennacables.

4.5.4 DVIDigital Video Interface is needed to connectdigital monitors like LCDs. Three types ofDVI connections exist: the DVI-A, which car-ries analogue signals only, the DVI-D, whichcarries digital signals only, and the DVI- I,which can carry both analogue and digi-tal streams. DVD-I sockets are the mostcommon.

4.5.5 HDMIHigh Definition Media Interface; a con-nector required to view High Definition

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Audio sockets

A VGA Connector

Coaxial plugs

A DVI—I plug

video on supporting hardware.This port is needed to view HDCP(High Definition ContentProtection) protected content.Unlike earlier devices, whichrequired separate audio and videocables, HDMI carries both signals.

4.5.6 RJ 45 / LANThis is the socket to connect aLAN cable (used for networking).

4.5.7 PCIPeripheral ComponentInterconnect, a 32-bit bus for datatransfer. Typically used to connectdevices like sound cards.

4.5.1 PCIEMotherboards usually carrytwo types of PCIE slots—PCIEX16 and PCIE X2.

4.5.8 PS/2 Mini DinThis is a six-pin socket used toconnect PS/2-compatible mice and keyboards.

4.5.9 RCAThis is the standard connector used for videoand audio output signals from standalonemedia players. RCA jacks are the preferredconnector for Composite and Componentaudio / video signals.

4.5.10 S-Video Mini DinThe Mini Din socket is seen in many graphicscards; it allows the signal to be displayed on a

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An HDMI plug and socket

An RJ 45 LAN socket

A pair of PCI slots

A PCI-E slot

A PS/2 mini din

An RCA connector

TV set. The S-Video standard port con-sists of a Mini Din connector with fourpins / sockets. But is it common tofind Mini Din connections with moresockets in some cards. The locations ofthe sockets are such that a 4-pin Mini Din plug for S-Video can stillbe fitted in such non-standard sockets.

Mini Din sockets / plugs are also used to carry power signals,and can be seen as power connectors in some devices like externaldrive bays.

4.5.11 SATASerial ATA is still only commonly seen on hard disks, though otherdevices like optical drives are also supported.

4.5.12 SerialIts importance has declinedafter USB devices became abun-dant,. Presently, mostly used toconnect devices like externalmodems.

4.5.13 USBAbundant in every system, with up to 10 USB connections (not allof them are on the back panel) per motherboard.

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The S-Video Mini Din on agraphics card

The SATA plug The SATA socket A SATA power plug

The good old serial port connector

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Mobile phones, iPods, PDAs, laptops: we carry these onour person like modern beasts of burden. While it’salways good to know, it’s even more important to know

the jargon and TLAs when it comes to personal devices!

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5.1 Laptops

5.1.1 Active MatrixThis is a type of display technology used in laptop screens, andsuch displays are also known as Thin Film Transistor (TFT) displays.These displays are made up of OLED pixels deposited on a grid oftransistors and capacitors. These transistors work as switches,enabling precise control of current flowing through the individ-ual pixels. The response times in this type of screen are very low,meaning the pixels can be switched on and off very fast. Thisensures that Active Matrix displays show sharp colours. They alsoconsume comparatively less electricity.

5.1.2 Desktop ReplacementsSuch laptops are not generally car-ried around much; they serve asreplacements for Desktop comput-ers. They typically have screen sizesfrom 17 to 20 inches. They are notoptimised for power savings, andhave limited battery life.

5.1.3 Docking stationA laptop accessory used to addfunctionality like extra opticaldrives, USB ports, PC Card slots,and keyboard or mouse connec-tors. Depending on the model oflaptop, they can be attached orremoved from the docking sta-tion without being restarted.Docking stations bring one thebest of both worlds—the mobilityof laptops and the expansion pos-sibilities of Desktops.

A desktop replacement laptop

A docking station for laptops

5.1.4 ExpressCardThis is a faster standardreplacing the PC Cardinterface, and is used innewer laptops. It wasintroduced in 2003, andcomes in two flavours—ExpressCard 34 andExpressCard 54. The num-bers represent the widthof the cards in mm.Devices that use thisinterface to connect to laptops are about 2.5 times faster thanthe PC Card interfaces, considerably lighter, and consume lesspower. Peripherals that can be used in the ExpressCard slotinclude wireless modems, TV-Tuner cards, memory sticks, andwireless modems.

5.1.5 Mobile ProcessorsProcessors used for laptops are built a lit-tle differently from their Desktop andserver counterparts. For one, they need toconsume less power, which is limited in amobile platform. Cooling options in lap-tops are limited: this requires the CPU toemit as little heat as possible. The twomain CPU manufacturers, AMD and Intel,both have a slew of products for themobile segment. These processors rangefrom single cores in older models to quadcores in newer ones. AMD’s mobile processor range includes prod-ucts like the dual-core Turion 64 X2 and Athlon 64 X2, and thesingle core Mobile Sempron, Mobile Athlon 64, and Turion 64.Intel markets mobile platforms under the name of Centrino,which collectively includes the processor, chipset, and wirelessnetwork adapter. Processors used in the Centrino platform arePentium M, Core Solo, Core Duo, and Core 2 Duo. The Centrino

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The new Express Card

The Centrino logo

platform has seen several implementations, like Carmel (2003),Sonoma (2005), Napa (2006), Santa Rosa (2007), and the proposedMontevina (2008) and Calpella (2009).

5.1.6 Passive MatrixThis is a screen technology used in older laptops. Here, the indi-vidual pixels are still referred to by row and column addresses, butthe amount of electricity flowing through individual pixels can-not be strictly controlled. This results in dull displays—effectively,pixels in a region of the screen can be manipulated, instead of sin-gle pixels. Additionally, response times are slower, resulting indull colours and low contrast. Some passive matrix based screensare HPA (High Performance Addressing), STN (Super TwistedNematic), and DSTN (Double-layer STN).

5.1.7 PC CardOriginally known as PCMCIA,this is a standard used for con-necting peripherals likemodems, network cards, andhard disks to laptop comput-ers. It is an IBM derived stan-dard, which has been usedwith laptops since the 1990s.They are divided into threetypes- I, II, and III. Type I PC cards are used for attaching memorylike Flash and SRAM. Type II is used for peripherals like modemand LAN cards, while Type III is used for connecting hard drives.The three types differ only in thickness; they are all 85.6 mm longand 54 mm wide. This standard is not as fast as other standardslike USB 2.0 and ExpressCard, but is still in use because of robustsupport by manufacturers.

5.1.8 PowerNow!This is AMD’s answer to Intel’s SpeedStep (see below). PowerNow!is integrated with Turion 64 X2, Mobile Sempron, Mobile Athlon64, and Athlon XP-M. PowerNow! has more variations in settings

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PC Card devices

than does SpeedStep. The latest Linux kernel has support forPowerNow! as well.

5.1.9 SO-DIMMSmall Outline Dual Inline Memory Module. SO-DIMMs are smallerin size than DIMMs, and are used mainly in laptop computers andalso in high-end printers and routers. There are four types of SO-DIMM, differentiated by the number of pins: 72, 100, 144, and 200.The performance parameters of SO-DIMMs are almost similar tothose of DIMMs.

5.1.10 SpeedStepA power management technology used in Intel’s MobilePentium processors. This utility allows software to change thefrequency settings and core voltage of the processor dependingupon the currently-running applications. Windows XP supportsthis feature natively, while older versions needed special driversto enable it. Linux distros as well as Mac OS X also supportSpeedStep. Enhanced SpeedStep is a more feature-rich version ofthe original technology; it enables up to five variations in speedand voltage settings, as opposed to SpeedStep’s low power modeand maximum power mode.

5.1.11 TouchpadAn input device for lap-tops, used to control thecursor using the motionsof the user’s fingers. Alsoknown as trackpads, theyare also found in PDAs andsome portable media play-ers. Touchpads have but-tons above or below them,which serve as the stan-dard mouse buttons.Touchpads also allow the use of multiple fingers for functionali-ties like click-and-drag.

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The touchpad in a laptop

5.1.12 UMPC“Ultra Mobile PC” is a cate-gory of small form factorPCs. The UMPC is a jointeffort of companies likeMicrosoft, Intel, andSamsung. These systemshave a 7-inch touchscreenand run standard operat-ing systems like WindowsXP or Linux. They feature aprocessor consuming low power (Intel Celeron M, Core Solo, orVIA C7-M). Typical specifications are 1 GB RAM, USB 2.0 ports,and hard disks ranging from 30 to 160 GB. Some UMPCs availablein the market are the Nokia N800, Samsung Q1, OQO, and theAsus Eee PC.

5.1.13 Ultra-portablesLaptops with screen sizes of lessthan 12 inches and which weighless than 3 kg (typically 1.4—2.3kg) are called ultra-portables.They have smaller-sized key-boards, and are targeted at fre-quent travellers. These laptopsare more expensive than regu-lar models and have extensivepower saving features. Mostmanufacturers have ultra-porta-bles in their product lines.

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Samsung’s Q1 was the original UMPC

Ultra-portables take a toll on your fingers

5.2 Mobile Services And Standards

5.2.1 1GThis is the first-generation telecommunication standard formobile phones. It was prevalent in the 1980s and early 1990s andused analogue radio signals. It has been almost phased out.

5.2.2 2GSuccessor to 1G, the second-generation standards used digital radiosignals. This meant that voice signals could be encoded and multi-plexed, resulting in more data being squeezed over the airwaves.The voice quality improved considerably, and the kind of staticheard on 1G networks is absent. The digital systems also emit lowerpower. Lower power means that the devices can be smaller, andthat the towers become more inexpensive to set up and maintain.

2G networks comprise mainly TDMA and CDMA networks,depending on the type of multiplexing i.e. the way in which themultiple radio waves are combined into a single stream. TDMAstandards can be further divided into GSM, iDEN, and more.Indian mobile networks are primarily 2G.

5.2.3 3GThird-generation networks deliver faster data speeds over existing2G networks and also more types of services like broadband accessand video telephony. The typical data transfer rates over 3G net-works are in the region of 5-10 Megabits per second. Depending onlocation, 3G networks use either the same spectrum as 2G (in theUS) or a different spectrum (in Asia and Europe). 3G-enabledphones are prevalent mostly in Europe and parts of Asia like SouthKorea and Japan. 3G-derived technologies include HSPA (HighSpeed Packet Access), WCDMA (Wideband Code Division MultipleAccess), and UMTS (Universal Mobile Telecommunication System).

5.2.4 4GFourth-generation wireless networks are intended to provide asolution where voice, data, and video can be accessed seamlessly

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without any bottlenecks. To be implemented using the IP protocolstack, 4G networks will provide connection speeds ranging from100 Mbps to 1 Gbps, with assured security, high quality, and lowcost. These networks will interoperate with existing networks anddeliver applications like real-time streaming video, HDTV, andhigh-volume data.

5.2.5 CDMACode Division Multiple Access is an alternative technology to GSMfor 2G and 3G networks. In CDMA, voice signals are digitised, andthe frequency of the transmitted signal is varied according to apredefined code. This signal can only be intercepted by a receiverwhose frequency response is programmed to vary with the samecode. Since there are trillions of frequency-shifting sequences,CDMA signals offer considerable privacy. These signals use the800 MHz and 1.9 GHz bands. CDMA signals utilise more band-width compared to GSM signals because of the variations in fre-quency. CDMA handsets are typically locked by carriers, whichmeans you cannot switch your carrier without changing yourhandset.

5.2.6 CSDCircuit Switched Data is a form of data transmission developed forTDMA networks like GSM. In this system, time slots are used todeliver data at the rate of 9.6 Kilobits per second. A newer variantis High Speed CSD (HSCSD) which employs more time slots andefficient coding methods to deliver data at enhanced rates.

5.2.7 EV-DOEvolution-Data Optimised is a 3G protocol for wireless data trans-mission used mostly for broadband Internet access. EV-DO usesCDMA to transmit data at speeds of 500 to 1000 Kilobits per sec-ond, and is not compatible with GSM networks. Where signalstrength is strong, EVDO enables a zone of pervasive computingwhere multiple devices can seamlessly use high-speed Internetaccess. Its primary competitor is HSDPA, which allows simultane-ous voice and data transmission.

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5.2.8 GPRSGeneral Packet Radio Service is a data transfer method usedwith GSM networks. In this method, data is transferred in pack-ets using the Internet Protocol (IP), rather than in streams. Datatransfer rates for GPRS vary from 56 to 114 Kilobits per second.It is a step slower than the EDGE (Enhanced Data GSMEnvironment) protocol, which delivers data at maximum ratesof 384 Kilobits per second. Apple’s iPhone is a GPRS / EDGEenabled device.

5.2.9 GSMGlobal System for Mobile communications is a 2G mobile net-work technology and currently the most popular globally, witha market share of more than 80 per cent. It is used by about 700operators in 214 countries, covering 29 per cent of the globalpopulation. In GSM, voice signals are digitised, then com-pressed, and sent along with two similar data streams in differ-ent time slots but the same frequency spectrum (900 MHz or1800 MHz). This indicates that it uses TDMA (Time DivisionMultiple Access) to send data. GSM networks also offer a degreeof data encryption.

5.2.10 HSPAHigh Speed Packet Access is based on the UMTS protocol. It is divid-ed into two standards: HSDPA (HS Downlink PA) and HSUPA (HSUplink PA). HSDPA is also known as “3.5G” and has theoretical datatransfer rates of 8 ~ 10 Megabits per second. Multimedia andstreaming video is the primary focus of HSDPA networks. Mostnew high-end phones come with HSDPA services enabled, thoughvery few carriers support these high speeds.

5.2.11 UMTSUniversal Mobile Telecommunication System is a 3G-based wire-less communication technology for cell phones using WCDMA asthe air interface. UMTS is also called 3GSM because the protocolwas intended to succeed GSM networks, and also used the GSMinfrastructure to connect.

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5.2.12 WAPWireless Access Protocol is designed to enable Internet access frommobile phones. This is done by using a special browser called aWAP browser (Opera Mini, for example), a simplified form of theDesktop browser, and accessing Web sites written in WML(Wireless Markup Language). Though WAP was projected to pro-vide full functionality for Web browsing in phones, the attempthas not been successful because of technical and design issues.

5.2.13 WCDMAWideband CDMA is a 3G standard for wireless data access and isdesigned to provide higher access speeds than the 2G GSM net-works. WCDMA is used mostly in Europe and Asia (particularlyJapan). It is called wideband because while CDMA transmits onone or more pairs of 1.25 MHz channels, WCDMA transmits dataon a pair of 5 MHz channels.

5.3 Mobile Phones

5.3.1 Bands (Dual- / tri- / quad-band)Mobile networks operate in different frequency ranges in differentcountries. When a phone is dual-band, it could, for example, workin the 800 MHz / 1900 MHz bands. Such phones are capable of oper-ating in different countries and take advantage of roaming services.

5.3.2 IMEIThe International Mobile Equipment Identity number is a 14-digitnumber used for identifying GSM handsets. Each handset has itsunique IMEI number and has no relation to the SIM. In case oftheft, the handset can be banned from accessing the networkusing the IMEI number, irrespective of whether the SIM card hasbeen changed or not. Various phone models have different keycombinations for displaying the IMEI—check your phone manualfor your key combination.

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5.3.3 MMSMultimedia Messaging Service is an extension of the commonly-used SMS, where audio, video, and rich text like animated iconscan be transmitted. It can work with packet data services like GPRSand EV-DO. MMS services need to be enabled on handsets. It is notas mainstream as SMS because of challenges like incompatibilitiesbetween the sender’s and recipient’s phones, network problems,and handset configuration.

5.3.4 PalmPalm is a proprietary embeddedoperating system for mobiledevices. It runs on smartphones,GPS devices, handheld gamingconsoles, etc. Palm supportstouchscreen actions with stylus orfingers, handwriting recognition,wireless connectivity, and multi-media capability, among otherfeatures. The current version is Palm 5.4. Somedevices using Palm OS are Treo and TX.

5.3.5 PDAPersonal digital assistants were originallysmall handheld computers used for tasks likereceiving e-mail, working on spreadsheets,word processing, etc. Newer PDAs have musicand video capabilities along with Wi-Fi andBluetooth functionality, making them jacks-of-all-trades.

5.3.6 S60This is the software platform for mobile phones that run on theSymbian Operating System (one of the OSes used on phones, apartfrom Windows Mobile). S60 has application libraries that supportapplications such as address books, music players, and camerasoftware. S60 also enables development of applications based on

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The Palm TX, aPDA runningon Palm

Palm on a watch

The iPaq, a PDAfrom HP

Java, Python, and C++. S60 was developed by Nokia and licensed toother companies. Other development platforms include BREWand Google’s new Android.

5.3.7 SIMThe Subscriber Identity Module is astamp-sized smart card that stores sub-scriber information for GSM phones.Additionally, it stores user informationlike preferences, contact lists, securitykeys, and text messages. SIM cardsenable the easy migration of user dataacross handsets and carriers.

5.3.8 Windows MobileMicrosoft’s compact operating system for mobile devices likesmartphones and PDAs. It is based onthe Win32 API and has a basic set offunctionalities. The latest version ofWindows Mobile is 6. The features ofthe Windows Mobile OS include OfficeMobile, Windows Media Player Mobile,QWERTY keyboard, and wireless sup-port. Devices that run WindowsMobile include the HTC Touch.

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SIM cards

A smartphone runningWindows Mobile 6.1

5.4 Cameras

5.4.1 AiAFArtificial Intelligence Auto Focus is Canon’s patented focusingtechnology, which dynamically selects one or more focussingpoints based on factors like subject position and motion. It alsodetects camera position, as in, the focus automatically changes ifthe camera is held horizontally or vertically.

5.4.2 ApertureThe iris-like structure that controls the amount of light falling onthe lens. The aperture is measured in f-stops. This range variesfrom f/1.4 to f/22, where f is the focal length of the lens.

5.4.3 CCD (Charge Coupled Device)A CCD is a light-sensitive integrated circuit. It stores colour infor-mation for every pixel as electric charge, whose intensity dependsupon the position of the colour in the colour spectrum. Thecharge for each pixel is read at one corner of the sensor and con-verted from analogue to digital. CCDs are used in digital camerasas sensors because they are extremely sensitive to colour varia-tions and create low noise.

5.4.4 CMOS (Complementary Metal-Oxide Semiconductor)CMOS is a technology that finds use in, among other things, cam-era sensors. It is the main competitor to CCD as a sensor technol-ogy. Though more susceptible to noise and less sensitive, theyconsume much less power, and are improving year after year interms of quality.

5.4.5 DigicDigital Image Core, or Digic, is a processor at the heart of any digi-tal camera. Introduced by Canon, the Digic processor removes noisefrom the electric signals generated when light falls on the imagesensor. It removes false colours, reproduces natural colours, and candeliver high-quality video and images even in adverse conditionslike subject motion and poor light. The latest version is Digic III.

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5.4.6 File FormatsDigital cameras store photographs in memory either in the JPEG,TIFF, or RAW formats. The TIFF and RAW formats do not apply anycompression while storing photos, while JPEG does. JPEG is morepopular with camera manufacturers due to the comparativespace savings over TIFF and RAW. However, compression causesloss of detail, and saving photos in JPEG is not a good idea if pro-fessional-quality photographs are what you want.

5.4.7 FramesA single photographic exposure is called a frame. A more impor-tant parameter is frame-rate, which is the number of exposures acamera can make in one second, and is measured in frames per sec-ond (fps). Generally this comes into play while shooting video, andthe higher the fps, generally, the higher is the quality of the video.

5.4.8 HistogramA graphical representationof the light and dark ele-ments in a photograph. Mostdigital cameras give one theoption of viewing the his-togram of a picture after it is shot. Photographs which are darkeror underexposed have peaks on the left side, while overexposedphotos have peaks on the right side. An evenly-distributed his-togram means that the image has been properly exposed.

5.4.9 Image StabilisationA technique used in many cameras to minimise the effects of lensshake. This problem is particularly noticeable when a tripod orsupport is not used, or at low shutter speeds. Sensors inside thecamera attempt to compensate for the vibrations that shakingcause by varying the path of the light rays to the sensor.

5.4.10 ISOA standard for measuring light sensitivity. The lower the ISO, thelower is the sensitivity of the film or sensor to light. This means

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Histograms show you the distribution oflight in your photo

that ISO 200 needs a lower exposure time or smaller aperture set-ting than ISO 100. Higher ISO settings are suitable for situationswhere the ambient light is low.

5.4.11 LensThe lens is one of the most important and expensive parts of a cam-era, and often makes the difference between a great photograph anda photograph. A camera may use a single lens, or a combination oflenses, which might be attached to the camera body, or detachable.Lenses are of many types, depending on what is being shot. Macrolenses are used to shoot at very small distances; telephoto lenses aresuitable for objects at large distances. Wide-angle lenses (like thefisheye lens) are used for situations that need a wider angle of vision.Another category is the zoom lens, whose focal length can be varied,and is most commonly seen in point-and-shoot digital cameras.

5.4.12 MacroA mode of photography where the subject is very close to the lens.Modern digital cameras have a setting for macro photography.

5.4.13 NoiseImperfection caused in the output from digital photos when thepixels are not sufficiently exposed to light. Too much noise makesthe finished photograph look grainy. Noise can be reduced by thecamera’s sensors, and also with the appropriate light settings.

5.4.14 Shooting modesA camera needs different settings for shooting photographs in dif-ferent scenarios. For example, shooting subjects at night needs adifferent aperture, ISO, flash settings, etc. than when shootingsubjects at the beach in daylight. Typical preset shooting modesthat modern digital cameras come with include Auto, Portrait,Night, Landscape, and Macro.

5.4.15 White balanceThis is a setting that makes it possible for objects that appearwhite to the eye appear the same in photos, irrespective of the

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lighting conditions (cloudy, dark, bright, filament light). Whitebalance settings are important because other colours are repro-duced in the photograph depending on the sensor’s perception ofwhiteness. Most digital cameras have automatic white balance set-tings, where the camera’s sensor tries to guess the brain’s percep-tion of the colours currently seen.

5.4.16 Zoom (Optical / Digital)Optical zoom is the amount by which a subject’s distance—as seenthrough the viewfinder—can be changed by changing the positionof the lens. This is done manually or by using tiny electric motors.Digital zoom, on the other hand, is simulated by the sensor in thecamera. In digital zoom, the camera crops part of the image andenlarges the remaining portion. This results in loss of detail. Forcameras, the optical zoom figure is much more important thanthe digital zoom, which can be simulated in image editing soft-ware like Photoshop.

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5.5 Connectivity

5.5.1 BluetoothA short-range (10 m-100 m) wireless con-nectivity standard used to connect awide variety of devices like music play-ers, mobile phones, digital cameras,and laptops over a secure network. Itconsumes low power and transfers dataat rates of 1-3 Megabits per second. Thelatest Bluetooth version is v2.1, whilethe faster v3.0 is in the works.

Bluetooth works without userintervention—a Bluetooth-enabled device continuously sends outvery low powered signals, and upon receiving a response fromanother compatible device, starts an auto identification process,which culminates in the transfer of data. Bluetooth is suitable forpersonal area networks (within a radius of about 10 metres) forcontrolling several devices seamlessly.

5.5.2 FireWireA high-speed interface, whosedevelopment was initiated byApple. It is also known as IEEE1394 High Speed Serial Bus. Itwas meant to be a replace-ment for the parallel SCSI bus,and also to provide connectiv-ity to audio and video equip-ment. Camcorders, memoryand storage devices, professional audio systems, etc. come withFireWire interfaces, as do several laptops. The data transfer ratesover FireWire interfaces at 400 Mbps is comparable to that of USB2.0, but unlike USB 2.0, the data flow rates can be sustained over alonger period of time. However, FireWire is more expensive becauseof licensing issues, and so is not as common as USB.

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A Bluetooth headphone set

FireWire connectors

5.5.3 InfraredInfrared is a region of the electromagnetic spectrum whose fre-quency is longer than that of visible light. Infrared is used inportable devices as a means of transferring data wirelessly. Thismight seem like Bluetooth and Wi-Fi, but has several disadvan-tages—it is line-of-sight (the two devices may not be separated byobstacles like walls), has a low data transfer rate, and is shorter-ranged. Some mobile phones as well as wireless keyboard andmice used to come with infrared ports; these have been replacedwith Bluetooth and / or Wi-Fi.

5.5.4 PictBridgeA camera industry standard. It usesUSB and cables to transfer data to aprinter from a camera without havingto connect to a computer in between,so a picture can be directly printed.Most new cameras and printers sup-port PictBridge.

5.5.6 Ultra WidebandA radio technology used for short-range, high-bandwidth (largerthan 500 MHz) communications. It consumes very low energy andis suitable for applications like wirelessly transferring media fromcamcorders or high-speed printers.

5.5.7 USBUniversal Serial Bus is an almost ubiquitous standard for con-necting devices like mice, keyboard, joysticks, printers, scanners,card readers, etc. to computers without switching off the system.USB comes in two versions—1.1 and 2.0, while a 3.0 standard isunder development. These standards are based on speed. USB 1.1transfers data at 1.5 to 12 Megabits per second, while USB 2.0transfers data at 480 Megabits per second. USB 3.0 is projected totransfer data at a maximum rate of 4.8 Gigabits per second. Acomputer can connect to a maximum of 127 USB devices directlyor by using hubs.

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The PictBridge logo

USB connectors are of two types—the A connector and the B con-nector. Most devices come with their own USB cables and they usethe A connector to connect to the computer. Devices that don’t havetheir own USB cables, like digital cameras, have a slot for the nar-rower B connector for connecting them to the computer.

There are other variants ofUSB connectors, like MiniUSB,MicroUSB, and Wireless USB.MicroUSB and MiniUSB are usedin smaller devices like mobilephones, while Wireless USB is ashort-range, high-bandwidth datatransfer standard using USB’sradio platform. Wireless USB isused in game controllers, digitalcameras, printers, scanners etc. Itis also used for streaming video.

5.5.8 WibreeA wireless standard developed by Nokia that is more energy-efficient than Bluetooth. Wibree transfers data at 1 Megabit persecond, but consumes about a tenth of Bluetooth’s power.Wibree is proposed to be used as a replacement for Bluetooth insports sensors, smart watches, and health monitors, wherepower supply is limited.

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The upper connector is type A, andthe lower one is miniUSB

5.6 Portable Media Players

5.6.1 Audio FormatsAll PMPs invariably support MP3 audio, so that music can be easi-ly swapped from your computer to your PMP and back, as MP3 isone of the most popular formats with a huge volume of existingmedia. Other formats supported are Microsoft’s WMA and also theopen source Ogg Vorbis. WMA reduces the size of MP3 files byalmost a factor of two, but due its proprietary nature, costs couldincrease. Ogg is technically superior in terms of compression, butlack of availability of media can be a problem.

AAC (Advanced Audio Coding) is a lossy compression and cod-ing scheme for audio, and is touted to be the successor to MP3.AAC delivers better quality than MP3 at the same bitrate. AAC isthe standard format used on the iPod and the iTunes store, and inthe PlayStation 3. Other music players that support AAC includethe Creative Zen and Microsoft’s Zune.

5.6.2 BitrateThe amount of data per second in a media file is known as thebitrate, and is expressed in kilobits per second (kbps). The higherthe bitrate, the higher would be the quality, and more storagespace would be needed. Bitrate can also be variable, in which therate at which data is packed in is varied over time. This means thatmore data can be stored for complex segments of media files,while lesser data is stored in simpler segments.

5.6.3 ConnectorsThe main types of ports in a PMP are the audio-out ports, whichare used to pipe music to speakers or headphones. Some PMPsoffer a TV-out port, which lets you hook it up to a large screen.USB and Mini USB ports are standard offerings for transferringmedia, along with power ports. iPods have a FireWire port, whichallows simultaneous charging and data transfer. The FireWireport can also be used to attach to external speakers and the ubiq-uitous iPod dock.

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5.6.4 DRMDigital Rights Management is the idea of controlling the playingof music across hardware. Music bought online is often digitallyencoded so that it cannot be shared. DRM has faced a lot of criti-cism; one example of DRM is Apple’s FairPlay mechanism.

5.6.5 EqualiserThis is a tool that allows one tomanually vary the emphasis ondifferent frequency bands whenan audio file is being played.Most playback software comeswith equalisers. The most common use of the equaliser is toincrease the bass, treble, and mid-range frequencies; those veryparticular about what they want their music to sound like mightuse all the sliders.

5.6.6 MP3 PlayersMP3 players are the most widely-sold person-al media players. They are called so becausethey primarily play MP3 audio files, thoughother formats like WMA are often supported.

5.6.7 SDA type of postage-stamp-sized Flash memorystorage used for extending the memory ofPMPs, cameras, and phones.

5.6.8 Skip ProtectionA technology used in music players to prevent music from playingirregularly when the player is jerkily moved. This was an impor-tant feature for CD and MiniDisc players because they containedmoving parts, and the read heads could be easily shaken. Skip pro-tection usually works by compressing data to a memory buffer andthen reading from it. This might result in lower quality because ofthe data loss during compression and decompression, but the ben-efit is uninterrupted music. Hard drive based PMPs do employ this

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The iPod Nano

An Equaliser diplayed by a music player

technology, but it is not an issue in Flash-based devices becausethey have no moving parts.

5.6.9 Video FormatsMPEG-4 video is widely supported by personal media players likeiPod and PSP. Windows Media Video (.wmv) is another supportedformat, while many manufacturers support DivX and XviD for-mats. There is not much difference between these video formats interms of quality, though open formats like MPEG-4 and XviD willhave lesser compatibility issues with hardware.

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For every piece of hardware you encounter, there’s an abun-dance of software for it running amok. This chapter coversall the terms you’re likely to encounter while you use them.

Software

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6.1 Operating Systems

6.1.1 AIXAdvanced Interactive Executive, an operating system developed byIBM, which is based on the UNIX operating system. It is typicallyused by larger enterprises, financial institutions, banks, etc. wherethere is a critical need for robust security features and mission-critical sturdiness. However, over the years, both Windows andLinux have narrowed this gap considerably.

6.1.2 LinuxBorn out of a geek’s inabilityto gain access to a freewareversion of UNIX, the Linuxoperating system, developedby Linus Torvalds, is amongthe most popular operatingsystems after Windows. Basedloosely on UNIX, Linux is anopen source operating system. For those of you who are scan-dalised by the prices that Microsoft charges for its licenses, afree operating system like Linux may just be the ticket. While itmay lack the glamour, razzle-dazzle, and spit and polish ofWindows, it is a highly stable system that can do most comput-ing tasks that you do in Windows without your being any theworse for it. There are many applications available for Linux,including replacements for Microsoft Officein the form of OpenOffice.

6.1.3 Mac OSThe Macintosh operating system from AppleComputer has been around since 1984, andwas the first operating system to introducethe graphical user interface (GUI). Since then,it has been overtaken by Windows, eventhough Mac users are quick to defend it andsay that the Mac OS is superior to Windows in

Linux as it is today

The latest iMac

every way. While this may be true, the Macintosh lost marketshare due to a number of factors, the primary one being thatApple insisted that it supply all the hardware and software forthe Mac. Windows, on the other hand was available on any PCthat supported the IBM PC standard. A combination of factorshelped Microsoft gain market share while the Mac OS lan-guished. Of late, there has been renewed interest in the Mac;more and more people have begun buying Macs again. In March2001, Apple introduced a new version of the Mac called Mac OSX (pronounced Mac OS ten). This was a complete rewrite of theentire Macintosh operating system and based on the UNIX oper-ating system core.

6.1.4 Operating SystemThe software that drives the computer. Over the years many oper-ating systems have been born (many more have died!). Commonlyreferred to as the “OS”, the operating system is the software thatcommunicates with the hardware and provides the environmentfor software applications to run. There are many different types ofoperating systems with some being created for a specific purpose.Popular examples of operating systems are Windows, Mac OS,Linux, UNIX and others. Even cell phones and PDAs have operatingsystems. Windows CE, Symbian OS and Palm OS are popularamong handhelds and PDAs.

6.1.5 ShellOn UNIX and UNIX-like systems, the shell is the section of theoperating system that interprets text commands for the comput-er execute. It is a command-line interface which means that anycommands have to be in text form only. The shell is just one layerabove the operating system and hence is a very powerful tool thatcan be used to do things that would normally be difficult with aGUI. In the right hands, the shell can be used to do perform pow-erful tasks like modifying files and folders; conversely, in thewrong hands, it could be devastating for your system. The shell inWindows is the DOS prompt that is still available for die-hardcommand-line fans.

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6.1.6 SolarisA version of UNIX from Sun Microsystems, it is legendary for itsindustrial-strength robustness and reliability. Before the advent ofLinux, Solaris used to be one of the most popular operating sys-tems for organisations looking for mission-critical systems thatwould remain operational 24x7. It had, and still has to someextent, a strong following in banks, financial institutions, andtelecommunication companies.

6.1.7 UNIXIt is an operating system that was developed in the 1960s andgained popularity in the 1970s. With the advent of the internetand the need for web servers UNIX and its variants gained atremendous boost in popularity and even to date is one of themost popular operating systems to run web servers. Its popularityis not unfounded as it is one of the most stable and rugged oper-ating systems. UNIX has many variants, the main one being Linux.

6.1.8 WindowsThe default operating system for more than 90 per cent of com-puter users the world over, this operating system from Microsoft iswhat most of us use day in and day out. Since the days of Windows3.1 when it really gained in popularity it has gone from strengthto strength and since then we have had Windows 95, Windows 98,Windows Millennium Edition, Windows 2000 Professional,Windows XP Home and Professional, Windows Vista Home Basic,Windows Vista HomePremium and Windows VistaUltimate. Windows 2000Professional and its predeces-sor Windows NT was designedfor business users which waslater enhanced to WindowsXP Professional. In WindowsVista Business, users have achoice of choosing eitherVista Business or Vista

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Vista heralds a new age for Windows

Enterprise. From Windows 3.1 to Windows Millennium Edition,the operating system was primarily based on the DOS system.From Windows XP the DOS technology used for the earlier operat-ing systems was abandoned in favour of the more robust technol-ogy based on the Windows NT technology.

6.2 General Software Terms

6.2.1 AIFFAudio Interchange File Format. An audio file format from Applecomputer for storing high quality audio. This is similar to theWindows WAV (wave) audio format in both audio quality and size.

6.2.2 Alert BoxA window that pops up on your screen with warnings generated byany running application which has encountered a special condi-tion, where you are required to be notified of the situation. An anti-virus program scanning your system, for example, would pop up analert box if it found something harmful.

6.2.3 ApplicationThis is a generic term for any software program that runs on thecomputer. Applications run within operating systems and assuch cannot be used between different operating systems. Thatis, an application that runs in the Mac OS will not under normalcircumstances run on a Windows or Linux system. There areexceptions to this rule but those are essentially feats of softwareengineering genius. Systems software is a special class of appli-cations and as such should be considered to be different fromapplications themselves.

6.2.4 BootIf you’ve ever been asked to boot up or reboot the computer andyou were not exactly sure as to what they meant, here is theskinny on that! Booting the computer is nothing more thanswitching it on. It’s been derived from the word bootstrap which

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was used at one time to help people put their boots on.Bootstrapping has passed into general usage from there andrefers to the process of using something small to start some-thing much bigger. Which is exactly what happens with a com-puter when it is switched on. When the computer is switchedon, a small computer program will run a basic test on all theessential hardware to ensure that it is responding correctly,wake up the motherboard and hard disk and call the systemfiles of the operating system as part of the boot process. Theoperating system will then take over from the boot file and loadall the required system files and driver software for the hard-ware. Once all the required files are loaded through thisprocess, known as the boot process, the operating system isready for use.

6.2.5 Closed SourceA closed source system is one in which the source code cannot beaccessed without the express permission of the owner of the soft-ware product. Much of the software these days is closed sourceand software companies charge a license fee for using their pro-gram. As compared to open source software, the license to the enduser only permits usage of the software product and does notallow them to reverse engineer the product or derive the sourcecode for the product.

6.2.6 DirectoryAlso known as a folder in Windows, a directory can contain otherdirectories or files. Directories are used to help in organising thefiles on your computer so that it is easily remembered for lateraccess. The structure of a directory is like a tree and as you moveup the tree you will finally reach the root directory of the drive.The root directory will contain many directories, usuallygrouped according to functions. Some directories are created bythe system and any modifications to the directory or its contentsshould be handled with extreme care. Other directories are cre-ated by application software where files necessary to its smoothoperation are stored.

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6.2.7 DriversAll hardware have a corresponding software that enables it to talkto the operating system, and through the operating system toother application software and/or devices. For example, printerdriver software enables the printer to communicate with the oper-ating system. Hence, when another application wants to print, itwill “ask” the operating system, which will in turn connect it tothe printer using the printer driver.

6.2.8 InstallerThis is a software program that installs applications and othersoftware onto your computer system. A typical application pro-gram may require many specific supporting system files before itcan run properly. Programmers use the installer software to pack-age all these files together. Depending on the size of the applica-tion, this could be a single file containing all the required data tocomplete the installation of the application software. The primarygoal of installer programs is to hide the complexity of the instal-lation process and to reduce the entire process to a point and clickoperation that can be used by any person whose knowledge ofcomputer systems is minimal.

6.2.9 Open SourceGenerally, open source refers to applications whose source codeis available for any one to see and modify in any way they please.In general practice, over the last thirty to forty years since thebirth of the software industry, software code has been consid-ered to be the property of the organisation who designed thesoftware, and anyone who used it was required to pay a licensefee for using the software. In the early 1970s, Richard Stallman, aresearcher at the Massachusetts Institute of Technology, took anideological stand against the use of proprietary software declar-ing that the right to read and modify the source code is a funda-mental right and that software should be open and free: “Free asin free speech, not free beer.” He came up with the GeneralPublic License (GPL) for open source software. The GPL essentiallystates that anyone who receives a copy of any software covered

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under the GPL simultaneously receives the entire rights to reador modify the source code. The giver may decide to either givethe software with the source code for free (as in “free beer”) orneed that the recipient pay some fee. In either case, the giver hasno right to restrict access to the source code. One of the moststriking examples of the open source movement is the develop-ment of the Linux operating system. This was an open collabora-tive effort that saw a full-fledged operating system evolve out of acomputer science student’s hobby.

6.2.10 Proprietary SystemsSee Closed Source.

6.2.11 Systems SoftwareIn addition to the core files that make up the operating system,there are a number of files and programs that are considered“part” of the operating system. These include software librariesof functions, system services, printer drivers, and other hard-ware, system preferences and configuration files—and muchmore. In contrast to applications, users have less choice as towhat parts of the systems software should be installed. In gener-al, systems software act as the first line of communicationbetween the hardware and the software.

6.3 Programming

6.3.1 ActiveXA technology from Microsoft used to view Desktop applications asWeb content. For example, using ActiveX, you can view MS Worddocuments or Excel spreadsheets in your Web browser.

6.3.2 ArrayProgrammers sink their teeth into arrays when they need to organ-ise data such that a related set of values can be easily sorted andsearched. An array is essentially a data structure that contains agroup of elements. Usually, the elements in the array are of the

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same data type, such as integers, strings, characters, etc. Usingarrays makes much more efficient use of memory than would havebeen the case if each value in the result had been assigned its ownvariable.

6.3.3 ASPActive Server Pages. A Microsoft technology, ASP is a scripted lan-guage that is processed by the Web server when a user accesses theWeb page. ASP pages can be quickly identified by their extension.asp, or .aspx, the more recent version of ASP. Like other scriptinglanguages used on the Web, the primary aim of ASP is to be ableto handle dynamic content, frequently-changing information, andaccessing other information systems like databases. ASP is basedon the Visual Basic programming language.

6.3.4 ASP.NetThis is a collection of Web development tools from Microsoft thatincludes software development programs like Visual Studio.NETand Visual Web Developer. These tools help programmers createdynamic Web sites by using a visual interface and using methodslike drag and drop. Often looked on as the next “version” of ASP(Active Server Pages) technology, ASP.NET’s support is not limitedto just Visual Basic.NET. It also supports Jscript.Net and opensource languages like Python and Perl. ASP.NET is built on the .NETFramework. For an ASP.NET site to function properly, it should runon a Web server that supports ASP.NET. By far, the Web server thatoffers the best support for ASP.NET is the IIS (Internet InformationServer) Web Server from Microsoft.

6.3.5 BASICBeginners All-Purpose Symbolic Instruction Code. Invented in themid-1960s, BASIC was meant to be a programming language forbeginners and students to quickly learn the concepts of program-ming. Since then, however, it has evolved into a robust language inits own right, and today there are versions of BASIC that are usedto develop application software. The most widely-used version ofBASIC is Visual Basic from Microsoft.

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6.3.6 Batch FileThis is a type of script used in Windows and DOS to automate cer-tain tasks. It is essentially a series of instructions that are execut-ed in sequence, and can either be invoked by the user or by a soft-ware program, or even when the computer starts up. Similar tasksin other operating systems like the Macintosh OS and UNIX areaccomplished by AppleScript and shell commands respectively.See also: Script.

6.3.7 Batch ProcessThe process of executing a series of instructions in a batch file isknown as a batch process. Typically, the batch process is used toexecute repeatable tasks that can be tedious to do manually. Forexample, if you need to copy a particular folder to a backup driveat the end of the day, you would write a batch file with the neces-sary instructions, and the system would initiate a batch process tocopy the files at the end of the day. The execution of the batchprocess is not limited to just Windows batch files. Any automatedtask that is set up to run can be considered as a batch process. Thiscould be accomplished by an appropriate scripting language onany operating system. See also: Batch File, Script.

6.3.8 BinaryWe normally write numbers in the Base 10 numerical system.Computer processors, however, can recognise only the on or off stateof the transistors in the chip. This leads to the need for a compatiblesystem of numerical notation. The binary system is a two-digitnumerical system, or a Base 2 system, comprising 1 and 0 (zero). Thisis much easier for computer systems to manipulate, as the on and offstates are easily represented as 1 or 0. And a combination of on andoff switches would be the equivalent of a number, a letter, or anyother character or group of characters. The number 110 (one-one-zero), for example, is the binary form of the base 10 number 6.

6.3.9 BooleanTo determine if a statement is True or False, computers use Booleanopearators. There are four main Boolean operators: AND, NOT, OR,

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and XOR. These logical operators are used together in complex waysto determine if a particular condition is True or False. Examples:

x AND y returns the value True if the condition is true for bothx and y or else it returns False

NOT x returns the value True if x is false (or null) and False if xis true

x OR y returns the value True if either or both x and y are true.It only returns false if both x and y are False for the given condition

x XOR y returns the value True only if either x or y are true. Ifboth x and y are true then it will return the value False.

Using Boolean operators is not restricted to computer pro-gramming. End-users also use Boolean expressions when theyneed to filter results in a search engine window. For example, theBoolean expression “computers AND hardware NOT memory”when used in a search engine will return all pages containing thewords “computers” and “hardware” while excluding all pages con-taining the word “memory”.

6.3.10 C/C++As programming languages go, C and C++ (pronounced C plusplus) are among the older languages that are still going strong. Cwas originally developed in the mid 1970s, and was primarilyused to write programs for the UNIX operating system. Sincethen, its use has expanded, and nowadays it is used to write appli-cations for nearly every available system. Those working onembedded technologies and hardware interfaces are particularlyenamoured by C due to its flexibility and efficient use of memo-ry. C++ is an offshoot of the C language with almost identical syn-tax. The main improvement that C++ has over C is that it supportsobject-oriented features that allow programmers great leaps inproductivity and efficiency.

6.3.11 CharacterAny number, alphabetical character, symbol, or punctuation markis a character. A computer assigns one byte for each character.

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6.3.12 Data TypeComputers store data in variables. Each variable will be of a pre-defined type. These types, or data types as they are more popular-ly known, include integers, floating point numbers, characters,strings, and arrays. Other data types include such things as date,timestamps, Boolean values, and varchar (variable character) for-mats. Some languages are more flexible and do not require thatyou explicitly assign a data type to each variable, and will assumethe data type from the first value assigned to the variable. This hasboth advantages and disadvantages. Data types are also an integralpart of database applications. Fields within a database should nor-mally be assigned to a specific data type.

6.3.13 DebuggingThe process of correcting the errors (or “bugs”) in a software pro-gram. Computer programs are long and complex pieces of code,and it is likely that there will be errors. A programmer has to gothrough the complete logic of the program and correct theerrors to the maximum extent possible before releasing the soft-ware to end-users.

6.3.13 DebuggerA program that is used to trace errors in the code as programmerswork on the program. It quickly identifies where exactly the errors(or bugs as they are called) are. The debugger will highlight the exactlines of code where problems are found. These bugs are usually relat-ed to errors in syntax representation in the programming languagethat’s being used. To find errors which are not obvious in the codeand are errors more related to the logic of the algorithm used orrelated to interaction characteristics with the system, debuggers alsosupport a step-by-step walk through of the program, which enablethe programmer to see how the application reacts to each line ofcode and where the code breaks or the system crashes.

6.3.14 Floating PointThis is a data type that contains floating decimal points. Thus37.001 is a floating point number, as compared to integers, which

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do not have decimal places. When a calculation includes a numberwith decimal places, the computer treats it as a floating pointnumber. Earlier computers used to have a separate processor tohandle floating point calculations, but nowadays, this ability isintegrated with the CPU.

6.3.15 IDEIntegrated Development Environment. Most programming lan-guages have a text editor that will highlight the source code basedon the syntax for the language, a compiler that will compile thesoftware program for execution by the computer, and a debuggerto debug the source code. In many instances, the three programsare separate from each other, and a software developer would needto open each program to accomplish the associated task. An IDEgives the developer a single development environment with theeditor, compiler, and debugger built into a single software system.In addition, depending on the compiler, it may support more thanone programming language, and also allow the developer to usevisual development tools especially for user interface development.Examples of IDEs are Visual Studio and Eclipse.

6.3.16 IntegerOne of the most commonly-used data types, integers are wholenumbers that can be positive, negative, or zero. Integers are notfractions or decimal numbers. Thus if the result of dividing twointegers produces a non-integer result, then the decimal numbersmay either be rounded or truncated to produce the integer result.

6.3.17 JavaA step up from C and C++, Java is theprogramming language of choice formany Web and software developers.Very similar to C and C++ in its syntax,it is object oriented but structuredaround “classes” instead of “func-tions.” To quote Sun Microsystems,the developers of the Java language,

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Java is a “simple, object-oriented, distributed, interpreted, robust,secure, architecture-neutral, portable, high-performance, multi-threaded, dynamic, buzzword-compliant, general-purpose pro-gramming language.”

6.3.18 JavascriptA scripting language with no relation to Java. Through some com-plicated convolutions of the politics of naming languages,Javascript inherited the Java prefix. Javascript is similar to otherscripting languages in that the code is executed as soon as it isread and does not require to be compiled as with normal sourcecode. However, there is one big, important difference betweenJavascript and the other scripts like PHP, ASP, and others:Javascript is not a server-side script, it is a client-side script. Thatis, the instructions in a Javascript file are executed by the user’sWeb browser and not by the server.

6.3.19 MacroA small program or script that is used to automate certain tasks. Amacro is usually a series of instructions that is recorded for a spe-cific application and may involve specific keystrokes or mousemovements. Applications like Word and Excel support macros forrepetitive tasks.

6.3.20 Null characterThis is a character that has all its bits set to zero, and hence has anumerical value of zero as well. It is used to represent the end ofa string and helps programmers determine the length of thestring. In databases and spreadsheet programs likes Excel, nullcharacters are used as space fillers.

6.3.21 Object-Oriented ProgrammingThis is a method of programming where data structures aretreated as “objects” rather than as variables. The main advantagewith object-oriented programming is that it enables the man-agement of very large software projects which if coded procedu-rally would have been almost impossible to support or extend. By

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having objects that interact with each other, the programmer isable to logically limit the problem to a specific subset, and needsto only ensure that the localised problem is dealt with—ratherthan having to pay attention to larger issues that are irrelevantin the context.

6.3.22 PerlPractical Extraction and Report Language. It is a scripting lan-guage with a syntax similar to C/C++ and is mainly used by Webprogrammers to create scripts for Web servers. It is especially goodat parsing text, so programmers often use it for reading andsearching through text files.

6.3.23 PHPHypertext Preprocessor.You may find it diffi-cult to imagine howthe expansion andthe acronym corre-late, but you will, ifyou delve into themysteries of computerlanguages, learn that it is arecursive acronym. Till such time, take it from us that PHP isindeed an acronym for Hypertext Preprocessor! PHP is an HTMLembedded scripting language for the Web. Much of PHP’s syntaxis borrowed from C, Java, and Perl, but it has its unique featuresand functions. When a user sends a request for a PHP page, theserver reads the PHP script that is embedded in the Web page, andtranslates the output into an HTML page which is then returnedto the user. Because users only see the HTML output and not theactual PHP code, PHP offers a higher level of security for accessingdatabases and other secure information. The aim of PHP is toallow developers to quickly and easily write code that can gener-ate dynamic pages.

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6.3.24 ScriptA computer script is exactly the same as the source code of pro-grams, but with one important exception. Application source codeis generally compiled before it is executed; a script, however, doesnot need to be compiled, and can be directly executed by thescripting engine. There are many scripts like PHP, ASP, JSP, DOS,VBScript, AppleScript, and so on. Each script has a correspondingscripting engine capable of reading and executing the instruc-tions in the script. See also Batch file.

6.3.25 Source CodeAll programs are written in one or the other programming lan-guage. The lines of text that comprise the program is known as thesource code. The source code (or source as it is usually called) canrun into tens of lines or into millions of lines. It contains variabledeclarations, functions, loops, instructions, and other statementsthat define the functioning of the program. Programmers oftenadd “comments” to their source to ensure that they and other peo-ple who look at the source will be able to read it easier than hav-ing to spend hours trying to decipher what exactly the algorithmdoes. A program will usually have many source code files, whichcan run into even thousands depending on the complexity of theprogram. For the program to run on a computer, the source codeneeds to be compiled so that it will be in a language that the com-puter can understand. If any changes are made to the source code,it will need to be recompiled for those changes to be incorporatedin the program.

6.3.26 StringA commonly-used data type, strings are used to represent textrather than numbers. A string is made of a group of characterswhich can include, text, spaces, numbers, and symbols. Even num-bers can be treated as strings if the correct syntax is used.Typically, strings are enclosed in double quotes to distinguish itfrom variables. Thus Data1 will be treated as a variable, while“Data1” will be treated as a string.

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6.3.27 SyntaxAll languages have a set of rules that define how the words andsentences are formed. Similarly, computer languages follow a setof rules that define how declarations, functions, commands, andother statements are arranged. This set of rules is known as thesyntax of the language. A program should have the correct syntaxfor it to run correctly. Even the lack of a parenthesis or a semi-colon can result in a syntax error. When a program runs into thou-sands of lines, it becomes next to impossible to discover syntaxerrors manually, so a debugger is used to identify errors.

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You can’t get anything done without having to deal with theInternet, or at least the office / home network today—you

might as well go into the field prepared.

The Network

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7.1 Technologies

7.1.1 ADSLAsymmetric Digital Subscriber Line. This is the technology used todeliver broadband over traditional copper telephone lines. Theterm Asymmetric denotes the difference between the downloadand upload speeds of broadband connections. Usually the down-load speeds are much higher than upload speeds in ADSL. So if yousee an advertisement for ADSL at 1 Mbps, most likely that’s thedownload speed. The upload speed maybe 256 or 512 Kbps. In com-parison SDSL (Symmetric Digital Subscriber Line) offers equivalentdownload and upload speeds. Almost always when you read aboutDSL in the media it normally refers to ADSL.

7.1.2 ATMAsynchronous Transfer Mode. For most of us, ATM stands forAutomatic Teller Machine, the place where you go withdrawmoney in the middle of the night, but ATM in the networkingworld is altogether a different kettle of fish! ATMs use 53-byte cellsto transmit data which due to its extremely small size and whencoupled with appropriate ATM switches results in transmissionspeeds of 600 Mbps. This kind of transmission speed can be used tosend all types of bandwidth hungry applications like videos andhigh resolution graphics.

7.1.3 Base StationOriginally the towers used by cell phone providers were known asbase station. With the advent of wireless LANs and Wi-Fi networks,the meaning of base station has been expanded to include thewireless access points that computers with wireless cards use tocommunicate. Essentially, a Wi-Fi base station is a router that con-nects all the computers within its range and also enables the usersto connect to the internet.

7.1.4 CAT 5Category 5. This is an Ethernet cabling standard and one of themost popular these days. To get speeds of 100 Mbps, you need to

use CAT5 cables. The term category 5 isused to indicate that this is the 5th gen-eration in cabling standards for twistedpair cables. Each category of cabling stan-dards describes the performance charac-teristics of the wiring standards.Category 5 is one of the best cabling stan-dards available today. It essentiallydepends on the number of twists perinch and the higher this number the bet-ter the performance of the wiring as it will reject noise and pro-vide greater bandwidth.

7.1.5 DSLDigital Subscriber Line—see ADSL

7.1.6 EthernetThis is a networking standard for Local Area Networks. In fact, thisis by far the most popular of all networking standards for LANs. Itsupports speeds of up to 10 Gigbits per second. However, what ismore common these days is 100 Mbps speed networks with selec-tive points operating at 1 Gbps. It used special grades of twistedpair copper wires for data transmission though the earlier ver-sions of Ethernet used co-axial cables. The name Ethernet wascoined by Robert Metcalf, one of its developers.

7.1.7 Fibre OpticsFibre optics is the process of transmitting information in the formof modulated light waves through very thin strands of pure glassbundled together. Because the information carrier is light, theinformation moves at the speed of light across the fibre-opticcable. One of the main uses of fibre-optics is in the area of long dis-tance communication, as fibre optic cables can carry enormousquantities of data.

7.1.8 SDSLSymmetric Digital Subscriber Line—see ADSL

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A CAT5 cable, exposed

7.1.2 Wi-FiThe wireless standard that is usedfor local area networking andInternet access, Wi-Fi ostensiblystands for Wireless Fidelity. Usingradio frequency technology, Wi-Firouters enable computers or lap-tops equipped with Wi-Fi adaptercards to communicate with each other or access an Internet accesspoint without the need to be physically connected to a cable. Thereare several Wi-Fi standards and Wi-Fi equipment are rated againstthese standards. The earlier standards were 802.11a and 802.11b, thecurrent standard is 802.11g. Standards a and g have a maximumthroughput of 54 Mbps and an active radius of about 30-35 metersindoors. Thus, if you would like to browse the Net while on your bal-cony, get yourself a wireless router; if you are using a laptop, chancesare it comes Wi-Fi enabled already.

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WiFi enabled devices come with thislogo

7.2 General Internet Terms

7.2.1 404 ErrorThe error page that is displayedwhen the site does not have therequested page. On many Websites, the 404 page is customised tomake it easier for humans tounderstand. When you see a pagewhich says something like “Oops! We couldn’t find the page youare looking for, please contact the site administrator” that’s actu-ally a customized 404 error page. (Also see 404 in Chapter 8under Internet Culture)

7.2.2 Ad Hoc NetworkA temporary network you quickly set up to transfer files or shareother information, or even play a networked game. For example,you may pop over to your friend’s house with your laptop anddecide to indulge in an impromptu game of Doom. You would thenuse a crossover Ethernet cable or hook up within the Bluetoothfield of your PCs.

7.2.3 AdwareThese are software programs distributed free, but with embeddedadvertisements. You will be required to watch the advertisementevery time you open the program. Most adware are clearly markedand you know what you are getting when you download andinstall the application but in other cases the software authors getthe software installed with out explicit permission from the enduser. They can also be particularly notorious for being hard touninstall and usually get installed on your system through decep-tive means by being bundled along with other freeware. Adware’sevil cousins are spyware (see spyware).

7.2.4 Anti-spywareSoftware programs designed to sniff out and remove any spywarelurking under the covers in your PC. It is become an essential

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A 404, done in style

part of the security arsenal of anysystem. (see also Anti-Adware andAnti-Virus)

7.2.5 Anti-adwareSoftware program that scans yourPC for adware and removes them.Like anti-spyware and anti-virus,this type of program has alsobecome the mainstay of your PC’s security blanket.

7.2.6 Anti-virusSoftware program that scans and and disinfects your PC from anyvirus programs. Most anti-virus programs these days scan for virus-es, adware as well as spyware.

7.2.7 AppletNot to be confused with the Apple computer company. The appletwas initially a reference to a small Java program that is embeddedin a Web page and in general refers to any application that is suf-ficiently small and usually runs within a Web browser. Appletsusually are not allowed to access system resources—files or devices(modems, printers, scanners, etc.)—as a security precaution againstanyone trying to maliciously take over the local computer.

7.2.8 Auto-responderIf you have ever received an automatic reply when you send amail to someone, what you have interacted with is the auto-responder. An auto responder is an e-mail message that is trig-gered to be send to anyone who sends a mail to the given e-mailaddress. This feature is particularly useful when you want to setout-of-office replies to be sent to anyone who sends you an e-mail when you are expected to be away from your office for alength of time.

7.2.9 BackboneAlso called the Internet backbone, this is the main link that con-

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Spybot Search and Destroy—anexample of anti-spyware

nects smaller networks in the Internet. The ISP who provides youwith the internet connection is the last link in a long chain oflocal, regional, national, pan-national, and international net-works that connect to each other through a global Internet back-bone. In one sense this is the main information highway alongwhich zips large volumes of data going to and fro across the globe.

7.2.10 BandwidthThis refers to the amount of data you can send through a modemconnection or through the network and is measured in bits persecond or bps. When you can send data in multiples of thousands,it is referred to as Kbps (Kilo bits per second) and in Mbps (Megabits per second). Most modern LANs operate at 100 Mbps. Thosewith the latest technology operate at 1 Gbps (Gigabits per second)or 1024 Mbps. In comparison, bandwidth through a dial upmodem is a measly 56 Kbps and through broadband DSL 256 Kbpsand upwards. We are just starting to see the spread of 1 Mbps andabove broadband connections.

7.2.11 Banner AdNearly 90 per cent of the Internet is run on advertising, and oneof the most ubiquitous tools used to deliver ads is the banner ad.This is the rectangular block of advertisement that you use at thetop of most Web pages. They are usually 468 x 60 pixels. Ads usedto be plain HTML with graphics and images, but these days as theinternet user gets more and more sophisticated banner ads havealso morphed. Nowadays banner ads use multiple gimmicks toattract the user including Flash movies, animations and more.

7.2.12 BCCBlind Carbon Copy. For anyone who has ever sent e-mail, the BCCfield is the one you use when you don’t want the main e-mailrecipient to know that the same message is being delivered to oneor more people other than the main recipient himself (or herself!).It is also a good practice, or netiquette as its known, to use BCCwhen you are sending a message to multiple people. By using BCCyou will be prevent one recipient from knowing the e-mail id of

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another recipient. This helps reduce the likelihood of any of therecipients trying to use the e-mail IDs in the mail for spamming.

7.2.13 BloatwareAny software that is stuffed with excessive features that have littleor no practical use, and degrades system performance instead.

7.2.14 BotnetEssentially an abbreviation for Robot Network. A botnet is a collec-tion of computers, usually thousands, that have been taken over bya specific group of hackers and are then used for their a specifictask or purpose. For example, the infamous Denial of Service attackon major Web sites are accomplished by using a botnet.

7.2.15 CacheA cache (pronounced ‘cash’) is a temporary location where infor-mation is stored for very fast access. There are many types ofcaches in a computer, starting from the processor which has acache known as the L2 cache. The operating system also has acache known as the virtual memory or swap file where informa-tion in the RAM is temporarily swapped to the hard disk when theRAM gets full. Similarly the Web browser also has a cache for Webpages that have been recently accessed.

7.2.16 CCCarbon Copy. A carbon copy is a term used to refer to the CCaddress in e-mail. The term is a carry-over from the days when car-bon copies were created for a letter needed to be sent to many peo-ple. When typing an e-mail message the To: field will contain theaddress of the main recipient and the CC field will contain theaddresses of all the other people who will receive a copy of themessage. The term has become so common in usage that nowa-days it is used as verb too: “I am CC-ing the mail to you as well!”

7.2.17 DOS Or Denial Of Service AttackThis is a type of attack on a Web site where the attacker tricks thesite to try and serve more pages than it possibly can, leading it to

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freeze to a halt and potentially crash the server. The motivation fora DOS attack can have many reasons, including financial profit orjust malicious fun.

7.2.18 DDOS or Distributed Denial of ServiceA DDOS attack would be what happens when a botnet is used tocarry out the attack. See Botnet and Denial of Service.

7.2.19 FirewallA software program or a hardwaredevice used to filter the data thatpasses between your computer ornetwork and the internet. Softwarefirewalls are directly installed onyour PC while hardware firewallsare connected to the entry point toyour network from the internet.

7.2.20 FreewarePrograms that you can use for free without having to pay anythingfor them. Some software authors may request a donation, but inessence, the software program is completely free to use whetheryou donate or not. In some cases, the freeware version will be theyounger cousin of a commercial offering of the same product. Thecommercial software will contain many more features than thefreeware. The freeware then becomes a marketing vehicle for thecommercial product.

7.2.21 HackerGenerally referred to as a person who hacks or breaks into com-puters. The term hacking has undergone a mind shift in the pastdecade or so and has evolved to mean something fun and enjoy-able. Hacking has evolved into a counterculture in its own rightand has also taken on heroic and romantic overtones much likethe ideas behind the likes of Robin Hood and the others. Hackerstry to distant themselves from their evil cousins, the ones whohack into computers or networks with criminal or harmful intent.

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Comodo is a software firewallused in Windows

In general both are known as hackers though a ‘good’ hackerwould call the ‘evil’ one a cracker.

7.2.22 ISPInternet Service Provider. The company who provides the internetconnection. Like with telephones and other utilities, the ISP willhave many tariff plans. Depending on your usage you can choosefor bandwidth limited or time limited plans or if you are a heavyinternet user you should look at the unlimited plans options.When you connect the internet through your broadband DSL con-nection or through a modem you are at the first level connectingto the ISP’s network, which will then connect you to a larger net-work or on to the Internet backbone. See also Backbone.

7.2.23 KeywordsA group of words that as accurately as possible describes every-thing about the subject matter. This could either be used in asearch engine or could be used as tags to a particular item. Forexample: “weapons technology secret program” is an example of aset of keywords you would use in a search engine. Tags are also anexample of keywords. When you tag a picture in Flickr you aremaking it easy for others to quickly find your picture when theysearch for matching or similar words.

7.2.24 LANThe grand daddy of networking. The Local Area Network. A LAN is acomputer network limited to a specific location like a building or anoffice or even the home. The LAN is the next step up from an Ad HocNetwork. Normally, LANs are created using switches and routers thatconnect multiple computers in a single location. LANs are usuallylimited to a small area where the computers are physically connect-ed to the network. Variations of the LAN include WAN—Wide AreaNetwork, MAN—Metropolitan Area Network and Wireless LAN orWLAN. WANs connect multiple LANs together using dedicatedleased lines or via VPNs over the Internet. MANs are WANs created toserve a large neighbourhood like a suburb or even an entire city initself. WLAN is the wireless version of the LAN normally using the

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WiFi standards of wireless technology. It essentially enables users atthe location to share information and resources, like printers etc,with each other. In the earlier days Novell used to be the defactochoice for networking software but these days Windows has more orless taken over the field completely. Most networks these days areEthernet based as it is relatively easy to deploy and robust enough togive trouble free service. However, with the advent of Wi-Fi technol-ogy there is a strong move towards wireless networks or wirelessLANs as they are called due to the relative ease of connection and thelack of the need for physical wiring in a location.

7.2.25 MANMetropolitan Area Networks—see LAN.

7.2.26 PANPersonal Area Network is thenetwork you create with yourdevices, usually using someform of wireless technology.Using Bluetooth to communi-cate between two PCs, your PCand your smartphone, transfer-ring files, etc. are all examplesof PANs in action.

7.2.27 SandboxAn isolated part of the system or network where new or unknownprograms are first installed and monitored for proper behaviourbefore being transferred to the main system. For example, all newWeb sites that Google’s search bot discovers are placed in a sand-box for a period of 60-90 days. They are then progressively madeavailable in the search engine results page.

7.2.28 Search BotShort for search robot. A software program that crawls the inter-net, runs though all the pages it finds and reports back to thesearch engine details of everything on the page. The search engine

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Multiple devices interacting viaBluetooth in a PAN

will index and classify these details in a myriad of ways that willthen be made available to the users when they search for the infor-mation based on the keywords they used in their search.

7.2.29 Search EngineGoogle, Yahoo, Windows Live areall examples of search engines.Using specialised software thatcrawl the World Wide Web,search engines indexes all thewords it finds on Web pages. Ofrecent, that is in the last fewyears, search engines havebecome extremely sophisticatedand not only index all the wordson a page but also try to correlate that with other bits of informa-tion regarding the said Web page gathered from other parts of theWeb. Thus, using complex algorithms search engines try to guessthe most accurate result that will satisfy the search request of theuser. Search engines have become one of the core pieces of the inter-net as everyone needs to search for some information or the otherat some point in time.

7.2.30 SharewarePrograms that are essentially ‘shared’ with you so that you can getto know how they work before you decide to buy it. Shareware pro-grams may have a set of ‘locked’ features that you can only gainaccess to after you buy the license for the product. The primary dif-ference between shareware and freeware is that shareware areusually time limited. For example one of the most popular com-pression utilities WinZip is actually a shareware product whichcan only be legally used for 15 days from the date of downloading.

7.2.31 SpywareThese are software programs that install silently in the back-ground without your knowledge. These programs then monitoreverything you do on the system, from the keys you press on your

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This is where you go to find stuff onthe Internet

keyboard to the sites you visit, the applications you open andwork with and so on. The gathered data is usually sent back to acentral server which is then processed and used in marketingproducts or even in hacking into the user’s account depending onthe program author.

7.2.32 TrojanA software program which is disguised as a legitimate programbut is actually a malicious piece of code that may infect and harmyour system. The name is based on the Trojan horse story from theGreek tragedy about Helen of Troy.

7.2.33 VirusA software program created to cause damage to your computer orto take over computer.

7.2.34 Virus definitionsViruses appear nearly everyday and therefore anti-virus vendorsneed to constantly update their anti-virus disinfection programsto counter the new threats. These updates are generally referred toas virus definitions or virus signatures.

7.2.35 WANWide Area Networks—see LAN.

7.2.36 WLANWireless LAN—see LAN.

7.2.37 Web HostA Web host at its very basic is a server which stores all the pagesof your Web site and is connected to the Internet. Users whorequest for information will be serviced by this Web server. It isalso used in reference to a provider of the server. Usually it ismore cost effective to just buy rental space on a Web hosting serv-ice provider to run your Web site. The Web site will run alongsidethousands of other small sites on a single server machine and isreferred to as shared hosting or virtual hosting. However, when

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users who simultaneously access the site increase, it will be nec-essary to have a single machine to ensure a consistent perform-ance and user experience. Large sites with thousands of pages ofinformation and millions of visitors will require hundreds ofmachines to ensure consistent performance.

7.2.38 WormA software program that self replicates spreading through out theNet. This is usually done by reading the address book on the infect-ed computer and then silently mailing itself out to all the peoplein the address book. The worms’ functions vary—some are harm-less, many are harmful.

7.3 Web 2.0

7.3.1 ASPApplication Service Provider. See SaaS.

7.3.2 JSPJava Server Pages. A Sun Microsystems technology, JSP is a scriptedlanguage that is compiled on the server rather than in the user’sWeb browser. JSP is based on the Java programming language andis used for building dynamic, database driven Web sites. Similar toPHP and ASP, all the code in a JSP page is processed by the Webserver and then send to the user.

7.3.3 SaaSSoftware-as-a-Service. Refers to offering software applications toend users on a rental or lease model where the user does not haveto worry about maintaining servers or people to manage the hard-ware and software infrastructure required to support the applica-tion. This is typically considered by organizations when they wantto procure and install expensive enterprise applications. An organ-isation which offers SaaS is referred to as an ASP or ApplicationService Provider.

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And finally, a chapter for items that fell under no other chap-ter, but which we had to include—the Enterprise IT section in

this chapter will be particularly useful, we think.

Everything Else

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8.1 Computer Science Fundamentals

8.1.1 AlgorithmA set of instructions that are defined to perform a specific com-puting task. This can be something as simple as performing addi-tion or something more complex like modifying an image in animage editor. Programmers spend a majority of their time creatingalgorithms that are then debugged to ensure that they work prop-erly and efficiently. The primary goal is to create efficient algo-rithms that use computing resources like RAM and CPU time withthe maximum efficiency. Obviously, when an algorithm is badlywritten, it will be a drag on performance.

8.1.2 AnalogueAnything that is read or accessed as a continuous stream is expe-rienced as analogue. Humans perceive everything in analogue—asa continuous stream of data and information to our senses.Similarly, the grooves in a record player or the magnetic datastored on an audio or video tape is typically a representation ofanalogue data. In comparison, digital is an approximation of theaudio or video signal. This means that analogue data is more accu-rate than digital data, but due to some inherent advantages withthe digital format, analogue is being slowly eliminated.

8.1.3 BespokeIn technology circles, a bespoke solution or system is somethingthat is custom-developed to meet the requirements of a specificneed. This can refer to both hardware and software. Typically anorganisation would go for bespoke software if there is no off-the-shelf software package that can meet their needs. Software devel-opers will then build a customised system to meet the require-ments. Typically, bespoke solutions are expensive, and with theincrease in commoditisation in the software market, more andmore solutions are coming out-of-the-box with customisation fea-tures rather than being 100 per cent bespoke. The cases where onlya bespoke solution will fit are rapidly shrinking from the generalmarketplace and are getting focused into niche segments.

8.1.4 DatabaseA system used to organise and store structured information foreasy retrieval and manipulation. A database contains tables madeup of rows and columns, and are used to store structured and hier-archical data like product details, employee information, etc.Databases today go beyond just storing textual information andcan now store sound clips, pictures, and video too.

8.1.5 DigitalInformation stored as a series of ones and zeroes is called digitalinformation. Humans perceive information in analogue; digitaldevices estimate this information using ones and zeroes. This esti-mation, known as sampling, is the process of storing the informa-tion in a tiny slice of time. This could be several times per second,and while it is imperceptible to the human ear or eye, there is atiny gap between two segments of information. A typical audio CDwould be sampled at 44.1 KHz (44,100 samples per second) with abit depth of 16 bits. This is a high-quality estimation of the audiosignal, and provides a level of audio quality that sounds good tothe ear. The major advantage with digital data is that it is mucheasier to copy, edit, and move without loss in quality.

8.1.7 End-userThe person who actually uses a software program. Among soft-ware developers, careful attention is paid to the wants and needsof the end-user when designing the program, as this person willeither drive the adoption of the program or cause its downfall.

8.1.8 GUI (Graphical User Interface)The graphical interface that we use with almost all computer sys-tems these days. Before the GUI was invented, the way to interactwith computer systems was through cryptic commands that weredifficult for the ordinary user to remember or even understand. AGUI made life much easier, enabling people to use features like thedragging and dropping of objects with a mouse rather than entertext commands.

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8.2 Upcoming Technologies

8.2.1 WiMAXWorldwide Interoperabi-lity for Microwave Access.In the rapidly-evolvingsphere of wireless tech-nology, WiMAX is thenext generation in wire-less access to the Internetwith speeds that areequivalent to cable orDSL connections. While Wi-Fi focused on providing wireless LANand Internet access, WiMAX is geared to deliver broadband accessover a range of 10 to 50 km at speeds varying from 10 to 70 Mbps.There are two main types of WiMAX: Fixed WiMAX and MobileWiMAX. Similar to cellular networks, the WiMAX service is pro-vided through a base station. In the case of Fixed WiMAX, you arelimited to the range of the base station; in the case of MobileWiMAX, you will be able to continuously access the Internet onthe move, and you would get automatic handover when you crossfrom the range of one base station to another. In India, we mayexpect to see WiMAX availability as early as 2008.

8.2.2 Mobile Broadband Wireless Access (MBWA)A technology standard still under discussion, being developedunder the aegis of the IEEE 802.20 standards group. It is expectedthat MBWA would have a range of 120 to 150 km.

8.2.3 Cloud ComputingThe term used to describe a kind of service where you can rentprocessor cycles and use them according to your needs. For exam-ple, if you wanted to do a complex maths problem that could onlybe comfortably handled by a powerful processor, cloud computingwould enable the user to gain access to server resources that couldbe used to complete the job. The user thus need not invest inequipment for tasks that may be more effectively rented out.


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A WiMAX PC card

8.3 Enterprise IT

8.3.1 Application ServerA server where a specific application or multiple applicationsreside. The application software on the server would connect tothe database on the database server. This kind of separationbetween the application server and the database server is both asecurity measure as well as performance optimisation method.

8.3.2 Business ProcessA word that is being increasingly encountered in the context ofsoftware discussions within organisations. A business processessentially is a series of interconnected activities that have a spe-cific start and a specific end. For example, a company may have apurchase process which starts with a requisition for materialsfrom a user; this requisition may result in triggering a request forquotes from vendors. Based on the vendor responses and afternegotiation, a vendor is selected and the purchase order issued.Based on the purchase order, the vendor supplies the materials. Hethen submits a bill to the accounting department. The accountingdepartment verifies his claims against the actual deliveries madeto the company stores and releases the payment. This entire cycle,which started with the user’s requisition and ended with thematerial being delivered and the payment being made to the ven-dor, is a simplified example of a business process cycle. In actualfact, business processes are much more complex, and require adetailed understanding of each user’s perspective in the link.Organisations seeking to improve their efficiency use businessprocess modelling tools to analyse how changes in the businessprocesses will impact the organisation.

8.3.3 CRMCustomer Relationship Management. Software that is used to per-form both the pre-sales management of the customers as well asthe post-sales follow up for services. During the pre-sales stage, asales force automation system provides the sales team with thetools and solutions to keep track of their potential customers and

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to monitor their progress till they become a confirmed order.After order confirmation, the relationship management would beshifted to appropriate people who would take care of the order ful-filment and post sales services.

8.3.4 Data CentreA facility where comput-er systems and associatedcomponents like storageand communications arehoused. Data centrespower much of theInternet, and it is anessential component inany enterprise thatmakes relatively exten-sive use of IT in its busi-ness. Irrespective of the fact that the data centre may be managedor owned by a third party, it is important that the centre be evalu-ated in terms of risk and reliability. That is, to the maximum extentpossible, the data centre operator should have taken precautionsagainst unknown factors like power failures and so on.

8.3.5 Database ServerUsually, a server hardware machine loaded with a database systemlike MySQL, SQL Server, Oracle, etc. The database system can beused by multiple application software programs to meet therequirements of various departments.

8.3.6 DMSDocument Management System. A software that stores multipletypes of documents including e-mails and faxes and even scannedcopies. Users can annotate notes to the documents, restrict accessto the documents using permission settings, and much more. It isuseful in organisations where there is a large amount of paper-based documents that need to be stored in an organised mannerfor easy and quick retrieval.


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A typical data centre

8.3.7 DMZDemilitarised Zone. A term borrowed from the army, the demili-tarised zone in technology is a computer or a small network insert-ed between the company’s private LAN and the public Internet.This is used to prevent and trap hackers from getting at companyinformation that resides securely in the private LAN. When hack-ers manage to break through the first layer of security, they wouldin all likelihood be trapped inside the DMZ under the false impres-sion that they are within the actual private network. This sense offalse security will give network security professionals sufficienttime to track and trace the intrusion attack.

8.3.8 DNSDomain Name System or Domain Name Service. Every domainname on the Internet has an associated IP address. The linkbetween the IP address and the domain name is managed by thedomain registry service at the InterNic, a global organisation.When a user types in a domain name—say thinkdigit.com—whathappens is that a query is sent to the Domain Registry asking forthe IP address of thinkdigit.com. This query and its resolution arehandled by the DNS.

8.3.9 E-CommerceThe business of transacting on the Net, where transactions are car-ried out in real-time or quasi-real-time. For example, a valid e-com-merce site would be one that sells various products online andallows the buyer to pay by credit card.

8.3.10 EDIElectronic Data Interchange. EDI was the forerunner to theInternet and acted as an electronic means by which trading part-ners could share information and transact with each other. Insome instances, the systems were so set up that when an itemreached below a specified quantity of stock, automatic purchaseorders were released from one company to the next via EDI. Thereceiving company would ship the item and inform via EDI thatthe items were shipped. While EDI is quite old technology, there

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are still many firms that rely on EDI and are unwilling to changetheir technology platform.

8.3.11 ERPEnterprise Resource Planning. A large and complex software sys-tem that integrates all the various departments of an organisa-tion under a single software solution. Given the name, the pri-mary task of the enterprise system is to optimise the use ofresources and to provide the organisation’s management teamwith analytical information that would be helpful in the makingof decisions and in the daily operations of the company. There aremultiple ERP software systems in the market, catering to widevariety of industries.

8.3.12 IntranetInternal networks in organisations that use Internet-relatedtechnologies, which normally would not be available on thepublic Internet.

8.3.13 Mail ServerServer software used to send, receive, and store the e-mail of allusers who have mail IDs in the organisation. Typically, dependingon the actual size of the organization, the mail server softwarecould either reside on a server or run off a normal PC. There aremany different kinds of mail server software. Commercial optionsinclude Microsoft Exchange and Lotus Notes. On Linux there are anumber of free mail server software available. Your choice woulddepend on the complexity of requirements. Consider whether thecompany’s e-mail needs to be administered centrally or whethereach individual user will manage his own mailbox.

8.3.14 MainframeThis is older technology from the mid-1960s that refuses to die out!In the ’60s, before the advent of the PC, access to computers wasexpensive. As a matter of course, many users would connect to asingle server-grade mainframe machine. Mainframes were built forreliability and stability, and as compared to standard PCs and serv-


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er technology, mainframes contain multiple CPUs running intodozens, have thousands of GB of RAM, and high-speed hard disksubsystems that can hold terabytes of data. Mainframes have aMean Time Between Failure (MTBF) rating of 20 years. Of late, inter-est in mainframes is being revived.

8.3.15 MilestoneIn project management terminology, a milestone is a key event ortask. The completion of this task will signal that the project hascompleted some important segment of the project. Each projectcan have multiple milestones.

8.3.16 OutsourcingTaking internal company functions and asking an outside agencyto do it. This may be due to cost advantages or because the com-pany may not have the required skills or manpower.

8.3.17 Project Management OfficeWhen an organisation has more than one major IT project beingimplemented, it becomes imperative that the processes be well-documented and the projects co-ordinated to ensure that there isno overlap and that there will not be any conflicts of personalityor even data. The project management office provides a formalmechanism by which multiple projects may be co-ordinated andimplemented in a structured and organised manner.

8.3.18 Remote AccessAccessing a remote computer and taking control over a computeras if you were sitting at it and using its mouse and keyboard. InWindows, such access is provided by RDP—Remote DesktopProtocol. Using RDP (which the user is unaware of, by the way) auser can request for assistance from a colleague or friend or fromthe organisation’s help desk. The help desk technician connects tothe user’s Desktop, takes over control, and rectifies the problem asif he were sitting at the user’s workstation. He then hands backcontrol to the user and disconnects the session. While Windowsuses RDP, Linux uses VNC or Virtual Network Computing to

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achieve the same effect. When connecting to a computer over theInternet, things can get tricky, as both RDP and VNC are not verygood at bandwidth management. Other software likeLogMeIn.com and GoToMyPC.com are commercial options to con-nect to your computer using an extended and enhanced version ofRDP / VNC. LogMeIn has a free version that provides basic remoteDesktop functionality, but without the management features youwould require if you are supporting multiple desktops.

8.3.19 ROIReturn on Investment. This is the magic number that financemanagers like to ask for and IT geeks like to dodge. The return oninvestment is the only true measure of the cost effectiveness ofyour IT investments. However, the difficulty is in determining theparameters on which ROI will be calculated. This requires that anyROI measurement be pegged to some business driver that is suf-fering due to lack of technological support. The decision to use thebusiness driver as the measure of ROI should be establishedthrough a consensus among the various project stakeholders. Forexample, a company may have a purchase process that is current-ly not efficient. A software has been identified which will improvethe efficiency of the process. To calculate the ROI, we would firstdetermine the cost of the current process and then compare itwith the revamped process. The difference in cost between the twoprocesses measured over a pre-agreed period of time will be thebasis on which the ROI calculation will be worked out. However,this approach has its drawbacks, and in some cases where thechange is not so readily visible, it may be that ROI is locked in tosome secondary process.

8.3.20 SCMSupply Chain Management. Company operations typically requirethat raw materials be bought from suppliers, be assembled ormanufactured, and the finished goods despatched to customers.The entire link from supplier to customer is what is known as thesupply chain. For organisations that want to create a competitiveadvantage, one of the areas of optimisation is the SCM segment


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that can lead to savings, and increase in efficiency, which in turnwould mean happier customers. SCM software provide this ability;however, SCM capabilities are often embedded into ERP software.

8.3.21 SEOSearch Engine Optimization. The process of fine tuning a Web siteso that it shows up in the search engines and ranks high in thesearch results for specific keywords that are relevant to the busi-ness of your company / site. SEO is an industry in its own right andthere are many theories as to how it should work. The basics, how-ever, remain simple and straightforward: create a Web site forhumans and not search engines, provide high-quality original con-tent that will be relevant to the audience who reads the pages onthe site, use CSS to the maximum extent possible, and ensure allyour HTML pages are properly meta-tagged with the right infor-mation and keywords.

8.3.22 ServerA rugged PC with fea-tures such as hot swap-pable drives—that is,hard drives that can beswapped out of the sys-tem without shuttingdown or opening the sys-tem; redundant powersupplies; and superiorcooling mechanisms dueto the amount of heatgenerated by the proces-sor. This kind of PCwould be designed to run 24x7. The operating system that runs onthis server hardware is also known as the server.

8.3.23 SFASales Force Automation; a subset of CRM. Many prospective cus-tomers may contact the sales team of your company, or converse-

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A server rack from HP

ly, your sales team may be in touch with many people. An SFA sys-tem will enable you to gather leads through various sources andconsolidate them in a single place. These leads would then be con-tacted and further qualified—and then converted into opportuni-ties, and finally to an order if and when the prospective customerdecides to buy.

8.3.24 SOAService-Oriented Architecture. Traditionally, software systems inorganisations were built to meet a specific need. However, this ledto a situation where a number of elements of data and businessprocesses would overlap each other in software. The service-ori-ented architecture is a system architecture mechanism that essen-tially provides the guidelines for creating and managing businessprocesses within the organisation. The business processes aredelivered as services that are supported by the IT infrastructure.Functionality is broken down into small distinct elements or serv-ices which can be distributed over the network, can be mixed andmatched together, and reused to create fresh business applica-tions. Finally, these services are able to talk to each other by pass-ing data from one service to another.

8.3.25 Technology StrategyThis is a broad outline that will explain in simple terms what acompany wishes to do in terms of information technology andhow this technology infrastructure ties in with the business planof the organisation. Depending on the size and complexity of theorganisation, the strategy may need to explore such issues as:building software versus purchasing off the shelf packages, thehardware infrastructure that should be standardised throughoutthe organisation, the software infrastructure that should be stan-dardised throughout the organisation, why it makes businesssense to go in for a specific technology initiative, and so on.

8.3.26 Unified CommunicationsThe merger of multiple modes of communication into a commoncommunication platform with the basic objective of ensuring that


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the sender and recipient are able to communicate with each otherirrespective of location or communication device. For example, avoice call to a person’s desk phone can be re-routed to his cellphone or email as a voice mail attachment.

8.3.27 VARValue Added Reseller. A VAR is an essential component in the salesand support of software. VARs are trained by the software andhardware companies to provide different levels of support to theend customer. Typically, VARs create their own, special packageson top of the main offering which acts as incentive to the prospec-tive buyer. For example a VAR of ERP software may decide to pro-vide a bundled offer to its customers which includes both the hardware and the software.

8.3.28 VirtualisationThe process of creating a virtual version of something such as anoperating system, a server, storage devices, or networkresources. Operating system virtualisation enables the user touse a software to run multiple operating systems on the samecomputer hardware. Some virtualisation software also allowsyou the capability of dynamically adding more hardware toincrease the power and range of the virtualised software. Thereare three main areas of virtualisation that are increasinglybecoming popular. One is network virtualisation, where thecombined bandwidth of the network is split into several chan-nels independent from each other and which can be assigned toa particular server or device in real time. By using virtualisa-tion, users need not be concerned with the underlying com-plexity of the actual physical network. The second is to consoli-date storage from multiple network storage devices into a singlevirtualised storage device that is managed from a single place.As far as the end-user is concerned, he will be dealing only witha hard disk, and will have no idea whether the drive is virtu-alised or not. The third is in server virtualisation, where a usermay have full access to a range of operating system services in avirtualised environment.

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8.3.29 VoIPVoice over IP. Here, “IP”stands for InternetProtocol. If a companymakes many internation-al calls, and has a broad-band connection, VoIPsoftware could save it aton of money. Typicalexamples of VoIP includeYahoo! Messenger,Google Talk, and Skype.In the traditional onlinechat services, users canchat with each other using the voice-enabled features of the soft-ware. With the extended features available in Yahoo! Messengerand Skype, users can call any land or mobile phone number (usingprepaid credits) at a very low cost. For some countries, the cost sav-ings can prove to be significant. Make sure you check the cost ofthe landline call and compare it with the VoIP service provider’scharges to calls in that country.

8.3.30 WBSWork Breakdown Structure. In project management terminology,the WBS is a detailed schedule of the project that shows the tasksand sub-tasks and the related timelines that each task will be com-pleted in. Each activity in a WBS will have a start date and enddate, and further, they may be constrained to not start before orend after a specific date. In addition, each task may be dependanton the previous task and linked to the task that follows. If the startor end dates for any task changes, then correspondingly, the startand end dates of all tasks linked to this task will change.


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Skype on a cell phone

8.4 Internet Culture

8.4.1 404Based on the infamous 404 error thrown by a Web server (see§7.3, General Internet Terms) the term has moved into generalusage where you might say “I’ve drawn a 404,” meaning “I’vedrawn a blank.”

8.4.2 AffiliateOne of the cornerstones of Internet marketing. Web site affiliatesand affiliate programs are used to generate leads and sales of bothphysical and digital download products. The affiliate industry hasevolved into a multi-million dollar sector. Affiliates normally earncommission on each item that’s sold by the site owner. TheInternet has made it extremely easy to track users who have cometo the site through the referral of a specific affiliate member.

8.4.3 Beta SoftwareThis has become de facto on the Web! Every new startup’s site is inbeta, probably having taken the lead from Google’s Gmail service.In actual fact, beta software is one of the stages of testing a soft-ware where the software (or site) is released to a limited numberof developers for live testing and reporting on bugs, crashes,errors, and other such problems. Software creation being a com-plex process, it is inevitable that the testers will not catch all thebugs. Thus, Web sites and software companies make the beta soft-ware available to the public to aid them in their testing process.Due to the large number of users testing the software simultane-ously, more and more bugs will be quickly discovered. This phe-nomenon led to the coining of the phrase: “Given enough eyeballs,all bugs are shallow,” as stated by Linus Torvalds, the creator of theLinux operating system.

8.4.4 Bounced messageTypically, an e-mail message that was not delivered and was“bounced” back to the inbox of the sender.

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8.4.5 ChatThe process of talking to a person over IM using the keyboard.

8.4.6 FlamingOne of the more serious sins when participating in online forumsis to start a flame war. When people begin discussing an issue in aplace like an online forum, there is a tremendous amount of opin-ion generated on all sides of the issue. During the process of dis-cussion and argumentation, some may feel offended and begin tomake insulting or caustic responses that will inevitably trigger asimilar reaction from the other party. And before one knows it,the entire thread of discussion has degenerated into a flame war,which is not useful to anyone. As a matter of good netiquette, it isalways advisable to walk away or hold your peace when you feelthat the online conversation may descend into a flame war.

8.4.7 IMInstant Messaging using an Instant Messenger like Yahoo!Messenger, Windows Live Messenger, Google Talk, Gaim, etc.

8.4.8 Voice chatChatting to other people either one-on-one or in conference using,for example, a software like Skype, complemented by headsets (ormicrophones and speakers). Almost all popular IM clients supportvoice chat nowadays


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